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Encode in Python and decrypt in Javascript
Question: I've searched for this, there are lots of hits, but I can't find one that is
neither complete (pulls all the bits together) nor says its a bad idea, use
HTTP. I've tried lots of things based on the hits I've found, but I can't get
it to work.
The target problem is to AES encrypt textual data at one place, send it to a
web API where it is stored in a database, then retrieve from the database via
another API and decode it in the browser. This is not for security in
transmission, it is so that, if the originator and the receiver know the key
and IV, then it can be stored without the server knowing what the real content
is.
The originator code is python, and the web API is python, so to make life
easier initially, I'm storing the content unencrypted in the database. I've
done AES encrypt/decrypt in python before, so that's not an issue. What I'm
trying to do is encrypt in python as the content comes out of the database,
transmit it, then decrypt in javascript. I've been using the python 'from
Crypto.Cipher import AES' code, and javascript CryptoJS implementation from
code.google.com
I'm happy at this stage to write the key and the IV into the code,
distribution isn't really a problem as the originator and the client browser
are effectively the same system.
I've not added any code because I think it would be more trouble than its
worth at this stage.
Thanks in advance!
OK, some code. On the server python(3) side:
text = 'This is a message'
key = 'This is a key123'
iv = 'This is an IV456'
text += (16 - len(text) % 16) * ' ' # Pad to 16 chars, spaces are OK here
aes = AES.new(key, AES.MODE_CBC, iv)
enc = base64.b64encode(aes.encrypt(text)).decode()
print(enc)
enc is passed along with other data, JSON encoded, as the response to an AJAX
request. On the client javascript side:
enc = /* from JSON */ ;
console.log(enc) ;
key = 'This is a key123';
iv = 'This is an IV456';
text = CryptoJS.AES.decrypt(Base64.decode(enc), key,
{ iv: iv, mode: CryptoJS.mode.CBC })) ;
console.log(text)
The python print(enc) and the javascript console.log(env) are the same, so I
know the b64'd encoded data is coming over OK. The console.log(text) (in
Chrome) shows as
l.WordArray.t.extend.init { ... }'
and not 'This is a message'. So why not!
Answer: **Solved, but another mystery**
I used the code from this gist:
<https://gist.github.com/andres-erbsen/1307675>
But: this uses code from <http://crypto-js.googlecode.com/files/>... which is
not what you get from the download at <https://code.google.com/p/crypto-
js/downloads/list>. The gist code uses Crypto.xxxx names; the download code
uses CryptoJS.xxxx names. The gist is 2 years old, has CryptoJS replaced
Crypto maybe?
|
Python: Using mpi4py to bcast an array to other scripts with spawn
Question: I'm trying to write two scripts, one a master and one a worker, where the
master script will spawn multiple processes of the worker and then bcast a
numpy array to the worker spawns. From looking at the number of (vague)
tutorials online for mpi4py, I feel like I understand this concept, but any
test code I've written won't successfully send the array to the workers. I
don't get errors, but they never receive the array.
Can someone please give me a clear example of how to use mpi4py, spawn, and
bcast to broadcast an array to a number of spawned worker scripts? Thank you!
UPDATE: Example:
Master script:
#! /usr/bin/env python
# master test
import sys,time
from mpi4py import MPI
import numpy as np
comm2 = MPI.COMM_WORLD
rank = comm2.Get_rank()
mpisize = comm2.Get_size()
initcomm = MPI.COMM_SELF.Spawn(sys.executable, \
args=['test2.py'], \
maxprocs=5)
# Initialise the programs
test = np.array([1,2,3], 'i')
print("About to broadcast {0} from rank {1}".format(test, rank))
initcomm.Bcast([test, MPI.INT], root=0)
initcomm.Disconnect()
Worker script:
#! /usr/bin/env python
# child test
import sys,time
from mpi4py import MPI
import numpy as np
comm2 = MPI.COMM_WORLD
rank = comm2.Get_rank()
mpisize = comm2.Get_size()
initcomm = MPI.Comm.Get_parent()
test = np.zeros(3, 'i')
print("Bcast coming to rank {0}".format(rank))
initcomm.Bcast([test, MPI.INT], root=0)
print("Received {0}".format(test))
initcomm.Disconnect()
Answer: You need to change Bcast in the master script to:
initcomm.Bcast([test, MPI.INT], root=MPI.ROOT)
If it's set to `0`, the master will think that the root is rank `0` in the
remote/worker group, and the program will hang.
|
Python dictionary having tuple keys and values
Question: What I like to have is a dictionary in the format of
`{(x1,y1):(a1,b1,c1),(x2,y2):(a2,b2,c2),(x3,y3):(a3,b3,c3),...}`
All the data is in a text file in a format like this:
x1 y1 a1
...
x1 y1 b1
...
x1 y1 c1
...
x2 y2 a2
...
x2 y2 b2
...
x2 y2 c2
...
I read the text file but I don't know how to associate the a, b, c values with
the corresponding key.
The script I have right now gives me `{(x1,y1):c1,(x2,y2):c2,(x3,y3):c3,...}`
which is not correct
Since I read the lines one by one, I am not sure how I can save the a , b
values.
Answer:
with open('path/to/input') as infile:
answer = {}
for line in infile:
x,y,v = line.split()
k = (x,y)
if k not in answer:
answer[k] = []
answer[k].append(v)
answer = {k:tuple(v) for k,v in answer.items()}
Of course, you could use `collections.defaultdict` to ease your burden just a
little:
import collections
with open('path/to/input') as infile:
answer = collections.defaultdict(list)
for line in infile:
x,y,v = line.split()
answer[(x,y)].append(v)
answer = {k:tuple(v) for k,v in answer.items()}
|
Getting Rethinkdb index metadata
Question: I'd like to obtain metadata about an index on a Rethinkdb table, such as
* what expression is used for arbitrary indexes
* what fields are used for compound indexes
* whether the index is multi or not
How can I get this information through the admin interface? Through the Python
API?
Thanks!
Answer: Unfortunately at this point you can't get any of this information. It's
something that's planned as an addition to ReQL but hasn't been added yet.
If this issue is important to you I'd recommend opening an issue here:
<https://github.com/rethinkdb/rethinkdb> that's the best way to influence
development direction.
|
How does os.path.join() work?
Question: Please help me understand how the builtin os.path.join() function works. For
example:
import os
print os.path.join('cat','dog') # 'cat/dog' no surprise here
print os.path.join('cat','dog').join('fish') # 'fcat/dogicat/dogscat/dogh'
On Mac (and i guess linux too) os.name is an alias for posixpath. So looking
into the posixpath.py module, the join() function looks like this:
def join(a, *p):
"""Join two or more pathname components, inserting '/' as needed.
If any component is an absolute path, all previous path components
will be discarded. An empty last part will result in a path that
ends with a separator."""
path = a
for b in p:
if b.startswith('/'):
path = b
elif path == '' or path.endswith('/'):
path += b
else:
path += '/' + b
return path
So join() returns a string. Why does os.path.join('something').join('something
else') even work? Shouldn't it raise something like 'str' object has no
attribute 'join'? I mean if I copy the function some other place and call it
like renamed_join('foo','bar') it works as expected but if i do
renamed_join('foo','bar').renamed_join('foobar') will raise an AttributeError
as expected. Hopefully this is not a very stupid question. It struck me just
when I thought I was starting to understand python...
Answer: You can't chain `os.path.join` like that. `os.path.join` returns a string;
calling the `join` method of that calls the regular string [`join`
method](http://docs.python.org/2/library/stdtypes.html#str.join), which is
entirely unrelated.
|
Log-In Automation
Question: I am trying to write a Python script that will automate logging in to a web-
client. This is to automatically log-in to the web-client with a provided user
name and password. Below is my Python code:
import httplib
import urllib
import urllib2
header = {
'Host' : 'localhost.localdomain',
'Connection' : 'keep-alive',
'Origin' : 'localhost.localdomain', #check what origin does
'User-Agent' : 'Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131029 Firefox/17.0',
'Content-Type' : 'application/x-www-form-urlencoded',
'Accept' : 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
'Referer' : 'http://localhost.localdomain/mail/index.php/mail/auth/processlogin',
'Accept-Encoding' : 'gzip, deflate',
'Accept-Language' : 'en-US,en;q=0.5',
'Cookie' : 'atmail6=tdl3ckcf4oo88fsgvt5cetoc92'
}
content = {
'emailName' : 'pen.test.clin',
'emailDomain' : '',
'emailDomainDefault' : '',
'cssStyle' : 'original',
'email' : 'pen.test.clin',
'password' : 'aasdjk34',
'requestedServer' : '',
'MailType' : 'IMAP',
'Language' : ''
}
def runBruteForceTesting():
url="http://localhost.localdomain/mail/index.php/mail/auth/processlogin"
for i in range (0,100):
data = urllib.urlencode(content)
request = urllib2.Request(url, data, header)
response = urllib2.urlopen(url, request)
print 'hi'
print request, response
runBruteForceTesting()
However: I am getting the following error:
Traceback (most recent call last):
File "C:/Users/dheerajg/Desktop/python/log.py", line 39, in <module>
runBruteForceTesting()
File "C:/Users/dheerajg/Desktop/python/log.py", line 35, in runBruteForceTesting
response = urllib2.urlopen(url, request)
File "C:\Python27\lib\urllib2.py", line 127, in urlopen
return _opener.open(url, data, timeout)
File "C:\Python27\lib\urllib2.py", line 402, in open
req = meth(req)
File "C:\Python27\lib\urllib2.py", line 1123, in do_request_
'Content-length', '%d' % len(data))
File "C:\Python27\lib\urllib2.py", line 229, in __getattr__
raise AttributeError, attr
AttributeError: __len__
Answer: The `request` object that you received from `urllib2.Request` does not have a
`__len__` method ; in your context, it means you're calling `urllib2.urlopen`
with a wrong second argument.
Looking at documentation, it is written it needs a string:
> data may be a string specifying additional data to send to the server, or
> None if no such data is needed.
So what about calling `urlopen` like this:
> response = urllib2.urlopen(url, request.get_data())
?
|
Can't set up a HTTP CGI Server in Python 2
Question: Does anyone notice this?
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from BaseHTTPServer import HTTPServer
from CGIHTTPServer import CGIHTTPRequestHandler
class Handler(CGIHTTPRequestHandler):
cgi_directories = ["/"]
httpd = HTTPServer(("", 8000), Handler)
httpd.serve_forever()
And the complete traceback:
Traceback (most recent call last):
File "server.py", line 6, in <module>
from CGIHTTPServer import CGIHTTPRequestHandler
File "C:\Python27\lib\CGIHTTPServer.py", line 30, in <module>
import SimpleHTTPServer
File "C:\Python27\lib\SimpleHTTPServer.py", line 27, in <module>
class SimpleHTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
File "C:\Python27\lib\SimpleHTTPServer.py", line 208, in SimpleHTTPRequestHan
ler
mimetypes.init() # try to read system mime.types
File "C:\Python27\lib\mimetypes.py", line 358, in init
db.read_windows_registry()
File "C:\Python27\lib\mimetypes.py", line 258, in read_windows_registry
for subkeyname in enum_types(hkcr):
File "C:\Python27\lib\mimetypes.py", line 249, in enum_types
ctype = ctype.encode(default_encoding) # omit in 3.x!
UnicodeDecodeError: 'ascii' codec can't decode byte 0xd7 in position 2: ordinal
not in range(128)
I used to run this code in the past and it works right, but now it simply
doesn't. The code works perfect in Python 3 (changing the imports).
Running Python 2.7.6 on Windows 8 (both 64 bits). Reinstalling Python doesn't
work.
Any ideas?
Thanks in advance.
Answer: Solved. This is an issue because of the encoding in the Windows registry
caused by the mimetypes module. If anybody find the same problem in the
future, [here](http://bugs.python.org/issue9291) is the patch to solve it. If
you don't want to waste your time checking that, here's the quick solution.
Replace the `enum_types()` function from the mimetypes module
(`Lib/mimetypes.py`) with this one:
from itertools import count
def enum_types(mimedb):
for i in count():
try:
yield _winreg.EnumKey(mimedb, i)
except EnvironmentError:
break
Thanks to all.
|
Excel (CSV) - transform header data to rows mapping with repeating rows
Question: I have Excel based data set which needs transformation. I would request a
Python based solution as I am learning Python and can read/modify the code
thereafter. I am OK with either an Excel or CSV based input/output.
**This is what my data looks like**
**Channel** **Condition** **Value1** **Value2** **Value3** _(Header)_
Channel A Condition B Live Live Pilot
Channel A Condition B Live Pilot Live
Channel B Condition C Pilot Pilot Pilot
Channel C Condition D Live Live Live
**This is the output I want:**
**Channel** **Condition** **Value(all)** *_Status_ * _(Header. I am OK if this
does not show up on output)_
Channel A Condition B Value1 Live
Channel A Condition B Value2 Live
Channel A Condition B Value 3 Pilot
Channel A Condition B Value 1 Live
Channel A Condition B Value 2 Pilot
Channel A Condition B Value 3 Live...
Basically it is a repetition of the Channel and Condition for each of the
"Values" which should be fetched from Column header and the dataset it self
(Live/Pilot).
I would appreciate some assistance as I have about 1000 rows of such
transformation to do
Here is an Image representing what I want 
Edit 2: There's a type on the screenshot. the Last 3 rows should read Channel
B, not Channel A.
Answer: Something like that should to the job.
import csv
transformed = []
with open('excel.csv', newline='') as csvfile:
r = csv.reader(csvfile, delimiter=' ', quotechar='|')
for row in r:
channel, condition, *vals = row
for val in vals:
transformed.append([channel, condition, val])
with open('transformed.csv', 'w', newline='') as csvfile:
w = csv.writer(csvfile, delimiter=' ',
quotechar='|', quoting=csv.QUOTE_MINIMAL)
for row in transformed:
w.writerow(' '.join(row))
|
Python BeautifulSoup give multiple tags to findAll
Question: I'm looking for a way to use findAll to get two tags, in the order they appear
on the page.
Currently I have:
import requests
import BeautifulSoup
def get_soup(url):
request = requests.get(url)
page = request.text
soup = BeautifulSoup(page)
get_tags = soup.findAll('hr' and 'strong')
for each in get_tags:
print each
If I use that on a page with only 'em' or 'strong' in it then it will get me
all of those tags, if I use on one with both it will get 'strong' tags.
Is there a way to do this? My main concern is preserving the order in which
the tags are found.
Answer: You could [pass a
list](http://www.crummy.com/software/BeautifulSoup/bs4/doc/#a-list), to find
either `hr` or `strong` tags:
tags = soup.find_all(['hr', 'strong'])
|
Debugging: Shuffle deck of cards in Python/ random
Question: I know the title sounds boring, because many people have already asked about
this topic. I hope it can help me get some insight into how the random module
works. The issue is, I wrote two different functions that I think should be
identical, but the results I'm getting are not identical, and I don't
understand why.
I hope to end up with a "well-shuffled deck." I only care about whether cards
are red or black, so my decks are very simple. I am calling "1" red and "0"
black.
My idea was to build the deck by appending a 1 (red) if random.random() is >
.5, or a 0 (black) otherwise, and then just appending 1 or 0 automatically
when I have reached 26 (half the deck) of one color. But something is going
wrong. deckmaker() doesn't work properly, although deckmaker2() does. Can
anyone provide insight?
import random
def deckmaker():
deck = []
for i in range(52):
if deck.count(0) == 26:
deck.append(1)
elif deck.count(1) == 26:
deck.append(0)
elif random.random() > .5:
deck.append(0)
else:
deck.append(1)
return deck
def deckmaker2():
newdeck = []
for i in range(26):
newdeck.append(0)
for i in range(26):
newdeck.append(1)
deck = []
for i in range(52):
x = random.randint(0,len(newdeck)-1)
deck.append(newdeck.pop(x))
return deck
Note: While writing this question I discovered the random.shuffle list
operator, which does the same thing as my second function, so of course
getting the shuffled deck turns out to be easy. But I still wonder why my
original code doesn't do the same thing.
**Edited:** Sorry for being vague about the exact problem with deckmaker().
The thing is, I don't exactly understand what's wrong. It has to do with the
fact that on the decks it produces, as you "turn over" the cards one by one,
there are strategies that let you predict whether the "next card" is going to
be red or black that don't work with decks created using random.shuffle
**Edit 2:** [lots more information] I will explain how I determined that
deckmaker doesn't work, in case that is important. I was writing this program
to model the puzzle posted here:
<http://www.thebigquestions.com/2013/12/17/tuesday-puzzle-4/>
My strategy was going to be to remember the last few cards dealt, and use that
information to determine when to decide to take the next card. I thought maybe
after getting 5 "black" cards in a row, it was a good time to predict "red." I
implemented it like so:
mycards = []
for j in range(1000):
mydeck = deckmaker(52)
mem_length = 5
mem = []
for c in range(mem_length):
mem.append(4)
for i in range(len(mydeck)):
if mem.count(0) == mem_length:
mycards.append(mydeck[i])
break
elif i == len(mydeck)-1:
mycards.append(mydeck[i])
break
else:
mem.append(mydeck[i])
mem.pop(0)
x = float(mycards.count(1))
print x/len(mycards)
The result more than half the cards I was taking (putting into the list
mycards) were "red," a result I achieved by taking the card after 5 _red_
cards in a row were drawn. This made no sense, so I looked for a different way
to create the decks and got a more normal result. But I still don't know what
was wrong with my original decks.
Answer: Generally speaking, you should never believe that a randomization approach
works correctly unless you can rigorously _prove_ it works correctly. And
that's often hard.
To get some insight into your problem, let's generalize the problematic
function:
import random
def deckmaker(n):
half = n // 2
deck = []
for i in range(n):
if deck.count(0) == half:
deck.append(1)
elif deck.count(1) == half:
deck.append(0)
elif random.random() > .5:
deck.append(0)
else:
deck.append(1)
return deck
And here's a little driver:
from collections import Counter
c = Counter()
for i in range(1000):
c[tuple(deckmaker(2))] += 1
for t in sorted(c):
print t, c[t]
Running that:
(0, 1) 495
(1, 0) 505
So the two possibilities are about equally likely. Good! Now try a deck of
size 4; just change the relevant line like so:
c[tuple(deckmaker(4))] += 1
Running that:
(0, 0, 1, 1) 236
(0, 1, 0, 1) 127
(0, 1, 1, 0) 133
(1, 0, 0, 1) 135
(1, 0, 1, 0) 130
(1, 1, 0, 0) 239
Oops! You could run a formal chi-squared test if you like, but it's dead
obvious by inspection that two permutations (the first and the last) are about
twice as likely as the other four. So the output isn't even close to being
arguably random.
Why is that? Think about it ;-)
**Hint**
For a deck of size `2*M`, what's the chance that the first `M` entries are all
0? There are two answers to that:
1. If all permutations of `M` zeroes and `M` ones are equal likely, the chance is 1 in `(2*M)-choose-M` (the number of ways to pick the positions of the `M` zeroes).
2. In the way the function constructs a deck, the chance is 1 in `2**M` (0 and 1 are equally likely in each of the first `M` positions).
Generally speaking, `(2*M)-choose-M` is very much larger than `2**M`, so the
function constructs a deck starting with all zeroes far more often than "it
should". For a deck of 52 cards (`M == 26`):
>>> from math import factorial as f
>>> one = f(52) // f(26)**2
>>> two = 2**26
>>> float(one) / two
7389761.998476148
So "starts with 26 zeroes" is over 7 million times more likely than it should
be. Cool :-)
**Doing it "one at a time"**
So is it possible to do this correctly picking a 0 or 1 one at a time? Yup!
You just need to use the right probabilities: when there are `nzero` zeroes
remaining to be picked, and `nremaining` total "cards" remaining to be picked,
pick zero with probability `nzero / nremaining`:
def deckmaker(n=52):
deck = [None] * n
nremaining = float(n)
nzero = nremaining / 2.0
for i in range(n):
if random.random() < nzero / nremaining:
deck[i] = 0
nzero -= 1.0
else:
deck[i] = 1
nremaining -= 1.0
return deck
Note that there's no need to count. When `nzero` becomes 0.0, the `if` test
will never succeed (`random() < 0.0` can't happen); and once we pick `n/2`
ones, `nzero == nremaining` will be true, and the `if` test will always
succeed (`random() < 1.0` is always true). It's cute ;-)
|
How does run.main() work?
Question: Please explain how following statement runs a Python script. There are no
custom function calls in this block:
if __name__ == '__main__':
import sys,os
import run
run.main(['', os.path.basename(sys.argv[0])] + sys.argv[1:])
Let me paste the entire script:
import wx
import wx.grid as grid
import wx.lib.mixins.gridlabelrenderer as glr
#----------------------------------------------------------------------
class MyGrid(grid.Grid, glr.GridWithLabelRenderersMixin):
def __init__(self, *args, **kw):
grid.Grid.__init__(self, *args, **kw)
glr.GridWithLabelRenderersMixin.__init__(self)
class MyRowLabelRenderer(glr.GridLabelRenderer):
def __init__(self, bgcolor):
self._bgcolor = bgcolor
def Draw(self, grid, dc, rect, row):
dc.SetBrush(wx.Brush(self._bgcolor))
dc.SetPen(wx.TRANSPARENT_PEN)
dc.DrawRectangleRect(rect)
hAlign, vAlign = grid.GetRowLabelAlignment()
text = grid.GetRowLabelValue(row)
self.DrawBorder(grid, dc, rect)
self.DrawText(grid, dc, rect, text, hAlign, vAlign)
class MyColLabelRenderer(glr.GridLabelRenderer):
def __init__(self, bgcolor):
self._bgcolor = bgcolor
def Draw(self, grid, dc, rect, col):
dc.SetBrush(wx.Brush(self._bgcolor))
dc.SetPen(wx.TRANSPARENT_PEN)
dc.DrawRectangleRect(rect)
hAlign, vAlign = grid.GetColLabelAlignment()
text = grid.GetColLabelValue(col)
self.DrawBorder(grid, dc, rect)
self.DrawText(grid, dc, rect, text, hAlign, vAlign)
class MyCornerLabelRenderer(glr.GridLabelRenderer):
def __init__(self):
import images
self._bmp = images.Smiles.getBitmap()
def Draw(self, grid, dc, rect, rc):
x = rect.left + (rect.width - self._bmp.GetWidth()) / 2
y = rect.top + (rect.height - self._bmp.GetHeight()) / 2
dc.DrawBitmap(self._bmp, x, y, True)
class TestPanel(wx.Panel):
def __init__(self, parent, log):
self.log = log
wx.Panel.__init__(self, parent, -1)
ROWS = 27
COLS = 15
g = MyGrid(self, size=(100,100))
g.CreateGrid(ROWS, COLS)
g.SetCornerLabelRenderer(MyCornerLabelRenderer())
for row in range(0, ROWS, 3):
g.SetRowLabelRenderer(row+0, MyRowLabelRenderer('#ffe0e0'))
g.SetRowLabelRenderer(row+1, MyRowLabelRenderer('#e0ffe0'))
g.SetRowLabelRenderer(row+2, MyRowLabelRenderer('#e0e0ff'))
for col in range(0, COLS, 3):
g.SetColLabelRenderer(col+0, MyColLabelRenderer('#e0ffe0'))
g.SetColLabelRenderer(col+1, MyColLabelRenderer('#e0e0ff'))
g.SetColLabelRenderer(col+2, MyColLabelRenderer('#ffe0e0'))
self.Sizer = wx.BoxSizer()
self.Sizer.Add(g, 1, wx.EXPAND)
#----------------------------------------------------------------------
def runTest(frame, nb, log):
win = TestPanel(nb, log)
return win
#----------------------------------------------------------------------
overview = """<html><body>
<h2><center>GridLabelRenderer</h2>
The <tt>wx.lib.mixins.gridlabelrenderer</tt> module provides a mixin
class for wx.grid.Grid that enables it to have plugin renderers that
work like the normal cell renderers do. If desired you can specify a
different renderer for each row or col label, and even for the little
corner label in the upper left corner of the grid. When each of those
labels needs to be drawn the mixin calls the render's Draw method with
the dc and rectangle, allowing your renderer class do do just about
anything that it wants.
</body></html>
"""
if __name__ == '__main__':
import sys,os
import run
run.main(['', os.path.basename(sys.argv[0])] + sys.argv[1:])
it appears that there is a run.py in the same directory with the script above:
#!/usr/bin/env python
#----------------------------------------------------------------------------
# Name: run.py
# Purpose: Simple framework for running individual demos
#
# Author: Robin Dunn
#
# Created: 6-March-2000
# RCS-ID: $Id: run.py 53286 2008-04-21 15:33:51Z RD $
# Copyright: (c) 2000 by Total Control Software
# Licence: wxWindows license
#----------------------------------------------------------------------------
"""
This program will load and run one of the individual demos in this
directory within its own frame window. Just specify the module name
on the command line.
"""
import wx
import wx.lib.inspection
import wx.lib.mixins.inspection
import sys, os
# stuff for debugging
print "wx.version:", wx.version()
print "pid:", os.getpid()
##raw_input("Press Enter...")
assertMode = wx.PYAPP_ASSERT_DIALOG
##assertMode = wx.PYAPP_ASSERT_EXCEPTION
#----------------------------------------------------------------------------
class Log:
def WriteText(self, text):
if text[-1:] == '\n':
text = text[:-1]
wx.LogMessage(text)
write = WriteText
class RunDemoApp(wx.App, wx.lib.mixins.inspection.InspectionMixin):
def __init__(self, name, module, useShell):
self.name = name
self.demoModule = module
self.useShell = useShell
wx.App.__init__(self, redirect=False)
def OnInit(self):
wx.Log_SetActiveTarget(wx.LogStderr())
self.SetAssertMode(assertMode)
self.Init() # InspectionMixin
frame = wx.Frame(None, -1, "RunDemo: " + self.name, pos=(50,50), size=(200,100),
style=wx.DEFAULT_FRAME_STYLE, name="run a sample")
frame.CreateStatusBar()
menuBar = wx.MenuBar()
menu = wx.Menu()
item = menu.Append(-1, "&Widget Inspector\tF6", "Show the wxPython Widget Inspection Tool")
self.Bind(wx.EVT_MENU, self.OnWidgetInspector, item)
item = menu.Append(-1, "E&xit\tCtrl-Q", "Exit demo")
self.Bind(wx.EVT_MENU, self.OnExitApp, item)
menuBar.Append(menu, "&File")
ns = {}
ns['wx'] = wx
ns['app'] = self
ns['module'] = self.demoModule
ns['frame'] = frame
frame.SetMenuBar(menuBar)
frame.Show(True)
frame.Bind(wx.EVT_CLOSE, self.OnCloseFrame)
win = self.demoModule.runTest(frame, frame, Log())
# a window will be returned if the demo does not create
# its own top-level window
if win:
# so set the frame to a good size for showing stuff
frame.SetSize((640, 480))
win.SetFocus()
self.window = win
ns['win'] = win
frect = frame.GetRect()
else:
# It was probably a dialog or something that is already
# gone, so we're done.
frame.Destroy()
return True
self.SetTopWindow(frame)
self.frame = frame
#wx.Log_SetActiveTarget(wx.LogStderr())
#wx.Log_SetTraceMask(wx.TraceMessages)
if self.useShell:
# Make a PyShell window, and position it below our test window
from wx import py
shell = py.shell.ShellFrame(None, locals=ns)
frect.OffsetXY(0, frect.height)
frect.height = 400
shell.SetRect(frect)
shell.Show()
# Hook the close event of the test window so that we close
# the shell at the same time
def CloseShell(evt):
if shell:
shell.Close()
evt.Skip()
frame.Bind(wx.EVT_CLOSE, CloseShell)
return True
def OnExitApp(self, evt):
self.frame.Close(True)
def OnCloseFrame(self, evt):
if hasattr(self, "window") and hasattr(self.window, "ShutdownDemo"):
self.window.ShutdownDemo()
evt.Skip()
def OnWidgetInspector(self, evt):
wx.lib.inspection.InspectionTool().Show()
#----------------------------------------------------------------------------
def main(argv):
useShell = False
for x in range(len(sys.argv)):
if sys.argv[x] in ['--shell', '-shell', '-s']:
useShell = True
del sys.argv[x]
break
if len(argv) < 2:
print "Please specify a demo module name on the command-line"
raise SystemExit
name, ext = os.path.splitext(argv[1])
module = __import__(name)
app = RunDemoApp(name, module, useShell)
app.MainLoop()
if __name__ == "__main__":
main(sys.argv)
Answer: In the file `run.py` there is a statement like this:
def main(args):
pass
You are importing run, and calling that `main` function.
The `__name__ == '__main__'` part just tells python not run execute that code
if the file is being `import`ed, only when run as a script.
* * *
I'm not sure of the contents of `run.py`, but
os.path.basename(sys.argv[0])
will give you the name of the script that is currently being called, so I'm
guessing that it is passing the script name and the first argument
(`sys.argv[1]`) to `run.main`, and that's how it knows how to run the script.
|
py2app ValueError: total_size > low_offset (164 > 0)
Question: I have a simple python script with two resources that I want to covert to an
Mac OSX app. Script runs fins from the command line, but when i try to package
it into an app, I get:
Ante-scriptum: I'm building in /opt/k which has the right permisions...
running py2app
creating /opt/k/build/bdist.macosx-10.8-x86_64/python2.7-standalone/app
creating /opt/k/build/bdist.macosx-10.8-x86_64/python2.7-standalone/app/collect
creating /opt/k/build/bdist.macosx-10.8-x86_64/python2.7-standalone/app/temp
creating build/bdist.macosx-10.8-x86_64/python2.7-standalone/app/lib-dynload
creating build/bdist.macosx-10.8-x86_64/python2.7-standalone/app/Frameworks
*** using recipe: virtualenv ***
*** using recipe: sip ***
*** using recipe: pyside ***
*** using recipe: email ***
*** filtering dependencies ***
468 total
66 filtered
9 orphaned
402 remaining
*** create binaries ***
creating /opt/k/build/bdist.macosx-10.8-x86_64/python2.7-standalone/app/temp/PySide
creating python loader for extension 'PySide.QtCore'
creating python loader for extension 'PySide.QtGui'
creating python loader for extension 'PySide.QtNetwork'
creating python loader for extension 'PySide.QtWebKit'
*** byte compile python files ***
byte-compiling /usr/local/Cellar/pyside/1.2.1/lib/python2.7/site-packages/PySide/__init__.py to PySide/__init__.pyc
creating /opt/k/build/bdist.macosx-10.8-x86_64/python2.7-standalone/app/collect/PySide
byte-compiling /usr/local/Cellar/pyside/1.2.1/lib/python2.7/site-packages/PySide/_utils.py to PySide/_utils.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/StringIO.py to StringIO.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/UserDict.py to UserDict.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_LWPCookieJar.py to _LWPCookieJar.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_MozillaCookieJar.py to _MozillaCookieJar.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/__future__.py to __future__.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_abcoll.py to _abcoll.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_osx_support.py to _osx_support.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_strptime.py to _strptime.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_sysconfigdata.py to _sysconfigdata.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_threading_local.py to _threading_local.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_weakrefset.py to _weakrefset.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/abc.py to abc.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/aifc.py to aifc.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ast.py to ast.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/atexit.py to atexit.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/base64.py to base64.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/bdb.py to bdb.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/bisect.py to bisect.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/calendar.py to calendar.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/chunk.py to chunk.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/cmd.py to cmd.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/codecs.py to codecs.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/collections.py to collections.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py to contextlib.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/cookielib.py to cookielib.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/copy.py to copy.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/copy_reg.py to copy_reg.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.py to ctypes/__init__.pyc
creating /opt/k/build/bdist.macosx-10.8-x86_64/python2.7-standalone/app/collect/ctypes
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/_endian.py to ctypes/_endian.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/wintypes.py to ctypes/wintypes.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/difflib.py to difflib.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/dis.py to dis.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/__init__.py to distutils/__init__.pyc
creating /opt/k/build/bdist.macosx-10.8-x86_64/python2.7-standalone/app/collect/distutils
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/dep_util.py to distutils/dep_util.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/errors.py to distutils/errors.pyc
byte-compiling /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/log.py to distutils/log.pyc
...
copying file /usr/local/Cellar/pyside/1.2.1/lib/python2.7/site-packages/PySide/QtWebKit.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/PySide/QtWebKit.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/MacOS.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/MacOS.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/Nav.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/Nav.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_AE.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_AE.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_Ctl.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_Ctl.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_Dlg.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_Dlg.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_Evt.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_Evt.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_File.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_File.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_Menu.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_Menu.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_Qd.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_Qd.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_Res.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_Res.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_Win.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_Win.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_bisect.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_bisect.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_codecs_cn.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_codecs_cn.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_codecs_hk.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_codecs_hk.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_codecs_iso2022.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_codecs_iso2022.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_codecs_jp.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_codecs_jp.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_codecs_kr.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_codecs_kr.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_codecs_tw.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_codecs_tw.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_collections.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_collections.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_ctypes.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_ctypes.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_elementtree.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_elementtree.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_functools.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_functools.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_hashlib.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_hashlib.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_heapq.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_heapq.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_io.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_io.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_locale.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_locale.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_multibytecodec.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_multibytecodec.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_random.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_random.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_scproxy.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_scproxy.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_socket.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_socket.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_ssl.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_ssl.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_struct.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_struct.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_testcapi.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/_testcapi.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/array.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/array.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/audioop.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/audioop.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/binascii.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/binascii.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/bz2.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/bz2.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/cPickle.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/cPickle.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/cStringIO.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/cStringIO.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/datetime.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/datetime.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/fcntl.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/fcntl.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/gestalt.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/gestalt.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/grp.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/grp.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/itertools.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/itertools.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/math.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/math.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/operator.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/operator.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/parser.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/parser.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/pyexpat.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/pyexpat.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/resource.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/resource.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/select.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/select.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/strop.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/strop.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/termios.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/termios.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/time.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/time.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/unicodedata.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/unicodedata.so
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/zlib.so -> /opt/k/dist/TestApp.app/Contents/Resources/lib/python2.7/lib-dynload/zlib.so
copying file test/blah/whatever.png -> /opt/k/dist/TestApp.app/Contents/Resources/test/Ikons/iphone_mail_icon.png
copying file test/jquery-1.8.3.min.js -> /opt/k/dist/TestApp.app/Contents/Resources/test/jquery-1.8.3.min.js
copying file test/jquery-ui.css -> /opt/k/dist/TestApp.app/Contents/Resources/test/jquery-ui.css
copying file test/jquery-ui.min.js -> /opt/k/dist/TestApp.app/Contents/Resources/test/jquery-ui.min.js
copying file test/jquery.jsPlumb-1.5.5-min.js -> /opt/k/dist/TestApp.app/Contents/Resources/test/jquery.jsPlumb-1.5.5-min.js
copying file test/normalize.css -> /opt/k/dist/TestApp.app/Contents/Resources/test/normalize.css
copying file test/phantomjs -> /opt/k/dist/TestApp.app/Contents/Resources/test/phantomjs
copying file test.htm -> /opt/k/dist/TestApp.app/Contents/Resources/test.htm
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/Resources/PythonApplet.icns -> /opt/k/dist/TestApp.app/Contents/Resources/PythonApplet.icns
copying file /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/py2app/recipes/qt.conf -> /opt/k/dist/TestApp.app/Contents/Resources/qt.conf
copying /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python -> /opt/k/dist/TestApp.app/Contents/MacOS/python
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/Resources
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/include
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/include/python2.7
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/lib
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/lib/python2.7
creating /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/lib/python2.7/config
copying /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/Python -> /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7
copying /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/Python -> /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7
copying /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/Resources/Info.plist -> /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/Resources
copying /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/include/python2.7/pyconfig.h -> /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/include/python2.7
copying /usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/config/Makefile -> /opt/k/dist/TestApp.app/Contents/Frameworks/Python.framework/Versions/2.7/lib/python2.7/config
Traceback (most recent call last):
File "setup.py", line 24, in <module>
setup_requires=['py2app'],
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/core.py", line 152, in setup
dist.run_commands()
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/dist.py", line 953, in run_commands
self.run_command(cmd)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/dist.py", line 972, in run_command
cmd_obj.run()
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/py2app/build_app.py", line 553, in run
self._run()
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/py2app/build_app.py", line 741, in _run
self.run_normal()
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/py2app/build_app.py", line 831, in run_normal
self.create_binaries(py_files, pkgdirs, extensions, loader_files)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/py2app/build_app.py", line 978, in create_binaries
platfiles = mm.run()
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/macholib/MachOStandalone.py", line 105, in run
mm.run_file(fn)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/macholib/MachOGraph.py", line 70, in run_file
m = self.createNode(MachO, pathname)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/macholib/MachOStandalone.py", line 19, in createNode
res = super(FilteredMachOGraph, self).createNode(cls, name)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/altgraph/ObjectGraph.py", line 165, in createNode
m = cls(name, *args, **kw)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/macholib/MachO.py", line 69, in __init__
self.load(fp)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/macholib/MachO.py", line 84, in load
self.load_header(fh, 0, size)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/macholib/MachO.py", line 114, in load_header
hdr = MachOHeader(self, fh, offset, size, magic, hdr, endian)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/macholib/MachO.py", line 154, in __init__
self.load(fh)
File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/macholib/MachO.py", line 247, in load
self.total_size, low_offset))
`
It's been driving me insane! I've installed macports, same error. Removed,
installed homebrew versions, same error.
Here's setup.py:
from setuptools import setup
APP = ['blah.py']
DATA_FILES = ['test', 'test.htm']
OPTIONS = {'argv_emulation': False}
setup(
name = "TestApp",
version = "0.9.0",
app=APP,
data_files=DATA_FILES,
options={'py2app': OPTIONS},
setup_requires=['py2app'],
)
Answer: Are you on Mavericks? I'm running into the same problem with a fresh install
of py2app on Mavericks. Looks like (in MachO.py) MachO is evaluating its
maximum allowable header size (low_offset) as zero, which of course makes no
sense.
In my case, it was happening at this line:
if cmd_cmd.filesize != 0 :
low_offset = min(low_offset, cmd_cmd.fileoff)
As a result of loading this module:
**.../lib/python2.7/lib-dynload/_mysql.so**
Right now my mySQLdb installation has a python version mismatch with certain
libraries I'm using, which may be the culprit. I was able to work around the
error by changing the above code in MachO.py to this:
if cmd_cmd.filesize != 0 **and cmd_cmd.fileoff != 0** :
low_offset = min(low_offset, cmd_cmd.fileoff)
By no means a satisfactory solution, but it allowed me to deploy a needed app.
When I resolve my python version mismatch, I will update with the outcome.
What worked for you?
|
Best practice way for linking object attributes to class or object
Question: I am looking for a reliable and pythonic way of giving class attributes of a
certain type a back-reference to the class they are connected to.
i.e. if there is class definition like the one below, I want to give
`SomeAttribute()` a reference back to the `SomeClass` type object.
class SomeClass(object):
attribute = SomeAttribute()
Currently I have an implementation that relies on a manual method call after
creating a class with this kind of attributes. (Example below). The problem
with the current approach is that a lot of code needs to check if the
reference class has already been populated to the attributes whenever they are
accessed.
One solution would be to require that the class is initialized, in which case
the code from `bind_attributes` could be placed into the `__init__` method.
However that obviously requires instantiating the class even if an instance is
not otherwise needed. I am sure a better solution could be implemented using
metaclasses, but I do not know how a pythonic implementation using a metaclass
would look.
import inspect
class Attribute(object):
def __init__(self, *params):
self._params = params
self._definition_class = None
def bind(self, definition_class):
self._definition_class = definition_class
def __call__(self):
return self._definition_class.separator.join(self._params)
class Definition(object):
separator = ', '
publications = Attribute('Books', 'Magazines')
clothes = Attribute('Shoes', 'Gloves', 'Hats')
@classmethod
def bind_attributes(cls):
for name, attribute in inspect.getmembers(cls, lambda m: isinstance(m, Attribute)):
attribute.bind(cls)
>>> Definition.bind_attributes()
>>> Definition.publications()
'Books, Magazines'
>>> Definition.clothes()
'Shoes, Gloves, Hats'
Answer: You can do this with a metaclass. For example:
class MyMeta(type):
def __new__(mcls, name, bases, members):
cls = type.__new__(mcls, name, bases, members)
for m in members.values():
if isinstance(m, SomeAttribute):
m.bound_cls = cls
return cls
Now of course one downside is this functionality is tied to the class rather
than the attribute, so every class you need this functionality with has to use
the metaclass:
class SomeClass(object):
__metaclass__ = MyMeta
attribute = SomeAttribute()
|
Camelot (Python framework): Specifying an Alternative EntityAdmin
Question: With the Camelot framework, models (subclassed from Entity) are defined with a
nested class (subclasses from EntityAdmin) that defines various gui properties
like layout and other widgets. The documentation indicates that multiple
EntityAdmins can be defined and then specified by the calling model:
> ### admin
>
> In case of relation fields, specifies the admin class that is to be used to
> visualize the other end of the relation. Defaults to the default admin class
> of the target class. This can be used to make the table view within a
> one2many widget look different from the default table view for the same
> object. [Camelot: Field Attributes man page](http://python-
> camelot.s3.amazonaws.com/gpl/release/pyqt/doc/doc/field_attributes.html#admin)
I can't seem to figure to figure out the required syntax. As a case study, can
anyone help me figure out how to do this with the "camelot-example" in the
package? (Camelot 13.04.13, Python 2.7.6)
Here is my example code:
from sqlalchemy.schema import Column
from sqlalchemy.types import Unicode, Integer
from camelot.admin.entity_admin import EntityAdmin
from camelot.core.orm import Entity, ManyToOne, OneToMany
import camelot.types
class Company(Entity):
__tablename__ = 'company'
name = Column(Unicode())
city = Column(Unicode())
employees = OneToMany('Employee')
def __unicode__(self):
return self.name or ''
class Admin(EntityAdmin):
verbose_name = 'Company'
verbose_name_plural = 'Companies'
list_display = ['name', 'city', 'employees']
field_attributes = {'employees': {'create_inline': True},
'admin': 'AlternativeAdmin'}
class Employee(Entity):
__tablename__ = "employee"
name = Column(Unicode())
age = Column(Integer())
company = ManyToOne('Company')
def __unicode__(self):
return self.name or ''
class Admin(EntityAdmin):
verbose_name = 'Employee'
list_display = ['name', 'age', 'company']
class AlternativeAdmin(EntityAdmin):
verbose_name = 'Employee'
list_display = ['name']
Note:
* "admin" under Company.Admin.field_attributes
* The "AlternativeAdmin" class
**This code runs without errors, but it does not work as intended**. The
company form displays an employee subform that shows name, age, and company.
It should just show company. I've tried the following for the "admin" value:
'AlternativeAdmin'
AlternativeAdmin
'Employee.AlternativeAdmin'
Employee.AlternativeAdmin
The error I get when uncommenting is:
NameError: name 'AlternativeAdmin' is not defined
I'm a self-confessed Python novice and I suspect some better Python
understanding could help me solve this.
I managed to find this via the great magic eight-ball (Google): A forum-poster
said this (sic), "Stupid me, I insisted in the alternate admin class being an
inner class just like the original one. Once I unnested it, it worked." He was
referencing this code:
class A(Entity):
...
class Admin(EntityAdmin):
...
class AdminEmbedded(EntityAdmin):
...
class B(Entity):
classA = OneToMany(...)
...
class Admin(EntityAdmin):
field_attributes = dict(classA=dict(admin=A.AdminEmbedded???))
Unfortunately, his grammar and/or spelling makes it hard to discern what he
meant. Also, I'm pretty sure there should be some quotes in there.
Answer: I figured it out. The answer induced a face-palm -- I left the
AlternativeAdmin class definition below where it was called after I un-nested
it. Once I moved it above, it worked fine.
Here is a full fixed version of the example in my question:
from sqlalchemy.schema import Column
from sqlalchemy.types import Unicode, Integer
from camelot.admin.entity_admin import EntityAdmin
from camelot.core.orm import Entity, ManyToOne, OneToMany
import camelot.types
class AlternativeAdmin(EntityAdmin):
verbose_name = 'Employee'
list_display = ['name']
class Company(Entity):
__tablename__ = 'company'
name = Column(Unicode())
city = Column(Unicode())
employees = OneToMany('Employee')
def __unicode__(self):
return self.name or ''
class Admin(EntityAdmin):
verbose_name = 'Company'
verbose_name_plural = 'Companies'
list_display = ['name', 'city', 'employees']
field_attributes = {'employees': {'create_inline': True,
'admin': AlternativeAdmin}}
class Employee(Entity):
__tablename__ = "employee"
name = Column(Unicode())
age = Column(Integer())
company = ManyToOne('Company')
def __unicode__(self):
return self.name or ''
class Admin(EntityAdmin):
verbose_name = 'Employee'
list_display = ['name', 'age', 'company']
|
error to append integer in c++ boost python list
Question: I does this code and not work
#include <boost/python.hpp>
namespace bp = boost::python;
int main(int argc, char **argv) {
bp::list points;
int one = 1;
int two = 2;
int three = 3;
points.append(one); #crach!!
points.append(two);
points.append(three);
return 0;}
which is the reason why "append" does not accept integers and directly which
would be the correct way?
**edited**
the solution is this:
#include <boost/python.hpp>
namespace bp = boost::python;
int main(int argc, char **argv) {
Py_Initialize(); //this part
bp::list points;
int one = 1;
int two = 2;
int three = 3;
points.append(one); #crach!!
points.append(two);
points.append(three);
Py_Finalize(); //this part
return 0;}
Answer: I think you are supposed to use `boost::python::list` from within the exported
module, not from a C++ program directly. The reason for this is simple:
`boost::python::list` is a wrapper around a Python list object and to work
with it you need a Python interpreter which is not available when you try to
operate on the list from your `main` method.
Here's a working example:
#include <boost/python.hpp>
namespace bp = boost::python;
bp::list getlist() {
bp::list points;
int one = 1;
int two = 2;
int three = 3;
points.append(one);
points.append(two);
points.append(three);
return points;
}
BOOST_PYTHON_MODULE(listtest) {
using namespace boost::python;
def("getlist", getlist);
}
Compiling this module and running the `getlist` function shows that everything
works as expected:
>>> import listtest
>>> print listtest.getlist()
[1, 2, 3]
|
Python Wave byte data
Question: I'm trying to read the data from a .wav file.
import wave
wr = wave.open("~/01 Road.wav", 'r')
# sample width is 2 bytes
# number of channels is 2
wave_data = wr.readframes(1)
print(wave_data)
This gives:
b'\x00\x00\x00\x00'
Which is the "first frame" of the song. These 4 bytes obviously correspond to
the (2 channels * 2 byte sample width) bytes per frame, but what does each
byte correspond to?
In particular, I'm trying to convert it to a mono amplitude signal.
Answer: If you want to understand what the 'frame' is you will have to read the
**standard** of the wave file format. For instance:
<https://web.archive.org/web/20140221054954/http://home.roadrunner.com/~jgglatt/tech/wave.htm>
From that document:
> The sample points that are meant to be "played" ie, sent to a Digital to
> Analog Converter(DAC) simultaneously are collectively called a **sample
> frame**. In the example of our stereo waveform, every two sample points
> makes up another sample frame. This is illustrated below for that stereo
> example.
sample sample sample
frame 0 frame 1 frame N
_____ _____ _____ _____ _____ _____
| ch1 | ch2 | ch1 | ch2 | . . . | ch1 | ch2 |
|_____|_____|_____|_____| |_____|_____|
_____
| | = one sample point
|_____|
To convert to mono you could do something like this,
import wave
def stereo_to_mono(hex1, hex2):
"""average two hex string samples"""
return hex((ord(hex1) + ord(hex2))/2)
wr = wave.open('piano2.wav','r')
nchannels, sampwidth, framerate, nframes, comptype, compname = wr.getparams()
ww = wave.open('piano_mono.wav','wb')
ww.setparams((1,sampwidth,framerate,nframes,comptype,compname))
frames = wr.readframes(wr.getnframes()-1)
new_frames = ''
for (s1, s2) in zip(frames[0::2],frames[1::2]):
new_frames += stereo_to_mono(s1,s2)[2:].zfill(2).decode('hex')
ww.writeframes(new_frames)
There is no clear-cut way to go from stereo to mono. You could just drop one
channel. Above, I am averaging the channels. It all depends on your
application.
|
PyOpenGL-accelerate + numpy
Question: I'm installing
[MakeHuman](http://www.makehuman.org/doc/node/overview_of_os_specific_installations_and_build_procedures.html)
on Debian, so all dependencies was set up, but when launching it's an error:
SYS.PLATFORM: linux2
PLATFORM.MACHINE: x86_64
PLATFORM.PROCESSOR:
PLATFORM.UNAME.RELEASE: 2.6.32.26
PLATFORM.LINUX_DISTRIBUTION: debian 6.0.6
NUMPY.VERSION: 1.6.2
OpenGL_accelerate module loaded
Using accelerated ArrayDatatype
Unable to load numpy_formathandler accelerator from OpenGL_accelerate
Unable to load registered array format handler numeric
Traceback (most recent call last):
File "makehuman.py", line 310, in <module>
main()
File "makehuman.py", line 300, in main
from mhmain import MHApplication
File "./core/mhmain.py", line 32, in <module>
import mh
File "./lib/mh.py", line 29, in <module>
from glmodule import updatePickingBuffer, grabScreen, hasRenderSkin, renderSkin
File "./lib/glmodule.py", line 33, in <module>
from OpenGL.GL import *
File "/usr/lib/python2.7/dist-packages/OpenGL/GL/__init__.py", line 3, in <module>
from OpenGL.raw.GL.annotations import *
File "/usr/lib/python2.7/dist-packages/OpenGL/raw/GL/annotations.py", line 40, in <module>
'v',
File "/usr/lib/python2.7/dist-packages/OpenGL/arrays/arrayhelpers.py", line 197, in setInputArraySizeType
function.setPyConverter( argName, asArrayTypeSize(type, size) )
File "arraydatatype.pyx", line 393, in OpenGL_accelerate.arraydatatype.AsArrayTypedSizeChecked.__init__ (src/arraydatatype.c:7688)
AttributeError: 'module' object has no attribute 'sizeof'
Does anyone solve problems with link PyOpenGL+ numpy?
Answer: fixed that on my system by issuing:
> sudo easy_install -U PyOpenGL
Noting:
* using Ubuntu 12.04 LTS, with python2.7
* did get a Permission denied error without that leading 'sudo'
* via: <http://matthew-4gl.wikispaces.com/python_modules> ( in turn from <https://bitbucket.org/ompl/ompl/issue/59/problem-with-ompl_apppy> )
good luck
|
How to install WTForms? Gettiing import error when trying to import forms
Question: I'm trying to follow the [Flask Mega
Tutorial](http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-
hello-world) for which I need to use WTForms. As is suggested in the tutorial,
I use a virtualenv in which I installed WTForms like this:
flask/bin/pip install flask-wtf
This seemed to work fine, and when I now run it again I simply get this:
Requirement already satisfied (use --upgrade to upgrade): flask-wtf in ./flask/lib/python2.7/site-packages
Requirement already satisfied (use --upgrade to upgrade): Flask in ./flask/lib/python2.7/site-packages (from flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): WTForms>=1.0 in ./flask/lib/python2.7/site-packages (from flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): Werkzeug>=0.7 in ./flask/lib/python2.7/site-packages (from Flask->flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): Jinja2>=2.4 in ./flask/lib/python2.7/site-packages (from Flask->flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): itsdangerous>=0.21 in ./flask/lib/python2.7/site-packages (from Flask->flask-wtf)
Requirement already satisfied (use --upgrade to upgrade): markupsafe in ./flask/lib/python2.7/site-packages (from Jinja2>=2.4->Flask->flask-wtf)
Cleaning up...
But when I try to import forms using `from forms import LoginForm` I get an
error saying: `ImportError: cannot import name LoginForm`.
Does anybody know what I'm doing wrong here, and how I can solve this? All
tips are welcome!
Answer: You need a module named `forms` that contains `LoginForm`,
from flask.ext.wtf import Form
from wtforms import TextField, BooleanField
from wtforms.validators import Required
class LoginForm(Form):
openid = TextField('openid', validators = [Required()])
remember_me = BooleanField('remember_me', default = False)
This is the example taken from [Part
iii](http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-iii-web-
forms).
|
Optimizing access on numpy arrays for numba
Question: I recently stumbled upon [numba](http://numba.pydata.org/) and thought about
replacing some homemade C extensions with more elegant autojitted python code.
Unfortunately I wasn't happy, when I tried a first, quick benchmark. It seems
like numba is not doing much better than ordinary python here, though I would
have expected nearly C-like performance:
from numba import jit, autojit, uint, double
import numpy as np
import imp
import logging
logging.getLogger('numba.codegen.debug').setLevel(logging.INFO)
def sum_accum(accmap, a):
res = np.zeros(np.max(accmap) + 1, dtype=a.dtype)
for i in xrange(len(accmap)):
res[accmap[i]] += a[i]
return res
autonumba_sum_accum = autojit(sum_accum)
numba_sum_accum = jit(double[:](int_[:], double[:]),
locals=dict(i=uint))(sum_accum)
accmap = np.repeat(np.arange(1000), 2)
np.random.shuffle(accmap)
accmap = np.repeat(accmap, 10)
a = np.random.randn(accmap.size)
ref = sum_accum(accmap, a)
assert np.all(ref == numba_sum_accum(accmap, a))
assert np.all(ref == autonumba_sum_accum(accmap, a))
%timeit sum_accum(accmap, a)
%timeit autonumba_sum_accum(accmap, a)
%timeit numba_sum_accum(accmap, a)
accumarray = imp.load_source('accumarray', '/path/to/accumarray.py')
assert np.all(ref == accumarray.accum(accmap, a))
%timeit accumarray.accum(accmap, a)
This gives on my machine:
10 loops, best of 3: 52 ms per loop
10 loops, best of 3: 42.2 ms per loop
10 loops, best of 3: 43.5 ms per loop
1000 loops, best of 3: 321 us per loop
I'm running the latest numba version from pypi, 0.11.0. Any suggestions, how
to fix the code, so it runs reasonably fast with numba?
Answer: I figured out myself. numba wasn't able to determine the type of the result of
`np.max(accmap)`, even if the type of accmap was set to int. This somehow
slowed down everything, but the fix is easy:
@autojit(locals=dict(reslen=uint))
def sum_accum(accmap, a):
reslen = np.max(accmap) + 1
res = np.zeros(reslen, dtype=a.dtype)
for i in range(len(accmap)):
res[accmap[i]] += a[i]
return res
The result is quite impressive, about 2/3 of the C version:
10000 loops, best of 3: 192 us per loop
|
Peewee ORM gives IntegrityError: user_id may not be NULL
Question: I'm trying to use the Peewee ORM for my new (Flask) website, and now I ran
into a problem. I just created a simple model like so:
from peewee import TextField, DateTimeField, IntegerField, ForeignKeyField
from app import db
ROLE_USER = 0
ROLE_ADMIN = 1
class User(db.Model):
nickname = TextField()
email = TextField()
role = IntegerField(default = ROLE_USER)
class Post(db.Model):
body = TextField()
timestamp = DateTimeField()
user = ForeignKeyField(User, related_name='posts')
So I created two users, after which I wanted to create a new post. I did this
like so:
>>> from app.models import User
>>> u = User(nickname='john', email='[email protected]', role=0)
>>> u.save()
>>> from app.models import Post
>>> from datetime import datetime as dt
>>> p = Post(body='FIPO!!', timestamp = dt.now(), author=u)
>>> p.save()
No handlers could be found for logger "peewee"
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/kramer65/dev/repos/microblog/flask/lib/python2.7/site-packages/peewee.py", line 2479, in save
ret_pk = self.insert(**field_dict).execute()
File "/Users/kramer65/dev/repos/microblog/flask/lib/python2.7/site-packages/peewee.py", line 1775, in execute
return self.database.last_insert_id(self._execute(), self.model_class)
File "/Users/kramer65/dev/repos/microblog/flask/lib/python2.7/site-packages/peewee.py", line 1470, in _execute
return self.database.execute_sql(sql, params, self.require_commit)
File "/Users/kramer65/dev/repos/microblog/flask/lib/python2.7/site-packages/peewee.py", line 1885, in execute_sql
return self.sql_error_handler(exc, sql, params, require_commit)
File "/Users/kramer65/dev/repos/microblog/flask/lib/python2.7/site-packages/peewee.py", line 1871, in sql_error_handler
raise exception
sqlite3.IntegrityError: post.user_id may not be NULL
I don't understand that user_id apparently is NULL, because as far as I
understand, peewee should take care of this right?
Am I doing something wrong (and if so; what?), or is this a problem with
peewee? All tips are welcome!
Answer: The problem is you're using `author=` when you should be using `user=`.
Original
p = Post(body='FIPO!!', timestamp = dt.now(), author=u)
Fixed
p = Post(body='FIPO!!', timestamp = dt.now(), user=u)
|
how can I subtract a method value from another method value in python?
Question: I've being trying to subtract a method value from another method value but it
gives me a an error even when I use variables.
from tkinter import *
statistics = Tk()
screenwidth = statistics.winfo_screenwidth
windowwidth = statistics.winfo_width
distance = screenwidth - windowwidth
statistics.geometry(+distance+'0')
Answer: You're trying to subtract two functions. You want to subtract the results of
calling the functions. Try this:
from Tkinter import *
statistics = Tk()
screenwidth = statistics.winfo_screenwidth()
windowwidth = statistics.winfo_width()
distance = screenwidth - windowwidth
statistics.geometry('+%s+0' % distance)
|
Merge CSV Files in Python with Different file names
Question: I'm really new to Python, so this question might be a bit basic. I have 44 csv
files with the same headers and different file names. I want to combine them
all into one file.
Each file is named "Votes-[member-name]-(2010-2014)-[download-time].csv"
The headers are do not include a column for the member name. I would like to
add that as the first item.
This does part of what I want to do: [how to merge 200 csv files in
Python](http://stackoverflow.com/questions/2512386/how-to-merge-200-csv-files-
in-python). I'm just not sure how to iterate through files with different
names, and add those names to the csv.
Thanks!
Answer: To iterate through the filenames you can use a similar method as answered
[here](http://stackoverflow.com/a/3964691/2327328), using glob:
import glob
import os
os.chdir("/mydir")
for files in glob.glob("*.csv"):
print files
Then, to add the member name to the header, you can print all the csv files
line by line. If the line is a header, then print the member name on the same
line as the header. (This isn't real code, but you can get the point)
for files in glob.glob("*.csv"):
for lines in files:
if line == header:
print member,line
else:
print line
To split the CSV file and only use the member name (slightly modified so to
not have a hyphen)
'Votes-[member name]-(2010-2014)-[download-time].csv'.split('-')[1]
**UPDATE for bash solution:** You can save this text and run it from the
terminal (see [instructions](http://stackoverflow.com/a/733901/2327328) here
for Mac)
Generate CSV files (not necessary)
cat <<"EOF" > 1.csv
1,2,3
4,5,6
EOF
cat <<"EOF" > 2.csv
a,b,c
d,e,f
EOF
_Parse CSV files_ \- this script takes all CSV files and writes their file
name as the first column. It also puts them into one file (note that I tested
on debian linux, not mac).
rm -f all.csv
for fyle in *.csv ; do
echo | awk -v f=$fyle '{ print f","$0 }' $fyle >> all.csv
done
exit 0
**SECOND UPDATE:** If you want to remove the duplicate headers, the simplest
way from the shell is to use 'grep -v', which selects all lines that don't
match. You can pick a generic string that only exists in the header.
head -1 all.csv > nohead.csv # add one header line
grep -v "header string" all.csv >> nohead.csv # add rest of rows, with no headers
|
Making CSV files easier to modify/navigate within Python using headers / column names?
Question: SO,
I have a CSV file with a varying number of columns which _I think_ means that
the traditional means of making headers as I have **attempted** below won't
work...
The reason I want some headers is because it gets incredibly difficult to use
csv files with 100+ columns and do things like `rPol =
math.exp((((-1.2359386)+float(row[48])*(row[33])+row[29]+row[13]+row[97]/row[50])))`
Trying to remember the identity of each row is a nussance, and it would be
much easier if I could do something like: `rPol =
math.exp((((-1.2359386)+float(depolscore)*(master_num)+ripen+offset_score+full/epilic)))`
import csv
reader = csv.reader(open("test.csv"), delimiter=",")
headers = {"data", "title", "here", "testing", "stackoverflow"}
csv.DictWriter(reader, headers)
reader.writeheader()
for row in reader:
print testing
How would I go about giving specific columns a header without doing something
like this:
for row in reader:
# put the columns into variables...
data = row[0]
title = row[1]
here = row[2]
testing = row[3]
stackoverflow = row[4]
# Do math
score = data * here / stackoverflow
# Print for user sake
print score
# Change the testing value
testing = testing + (score - title)
# Put values back into the reader object?
row[0] = data
row[1] = title
row[2] = here
row[3] = testing
row[4] = stackoverflow
Any ideas?
Answer: You could try using a
[namedtuple](http://docs.python.org/2/library/collections.html#collections.namedtuple)!
It's a subclass of tuple, allowing for easy creation from an iterable and easy
access to fields by name. The only gotcha you should be aware of is that
namedtuples, like tuples, are immutable so you'd have to store the new tuples
somewhere:
headers = ["data", "title", "here", "testing", "stackoverflow"]
Row = namedtuple('Row', headers)
for raw_row in reader:
row = Row._make(raw_row)
# Do math
score = row.data * row.here / stackoverflow
# Print for user sake
print score
# Change the testing value
new_testing = row.testing + (score - row.title)
new_row = row._replace(testing=new_testing)
# Do something with new_row...
|
Paginator in python django crashes on dict
Question: I have 2 types of gathered data from database:
One is `[<NaseljenoMesto: NaseljenoMesto object>, <NaseljenoMesto:
NaseljenoMesto object>]`
And another is: `[{'naseljenomesto_drzava__naziv': u'Srbija', 'sifraMesta':
u'ZR', 'nazivMesta': u'Zrenjanin', 'id': 3}, {'naseljenomesto _drzava__naziv':
u'Srbija', 'sifraMesta': u'BG', 'nazivMesta': u'Beograd', 'id': 1}]`
First is QuerySet type and another is ValuesQuerySet.
Now i have Paginator: `paginator = Paginator(filteredData, rowsPerPage)`
In first case paginator works but in second crashes. How to correct this?
## EDIT
Internal Server Error: /TestProjekat/main/getFormData/
Traceback (most recent call last):
File "C:\Python27\lib\site-packages\django\core\handlers\base.py", line 115, in get_response
response = callback(request, *callback_args, **callback_kwargs)
File "C:\Users\Milan\Desktop\DA_LI_RADI\Test projekat\st_forms\views.py", line 238, in getFormData
serializedData = serializers.serialize("json", data)
File "C:\Python27\lib\site-packages\django\core\serializers\__init__.py", line 99, in serialize
s.serialize(queryset, **options)
File "C:\Python27\lib\site-packages\django\core\serializers\base.py", line 46, in serialize
concrete_model = obj._meta.concrete_model
AttributeError: 'dict' object has no attribute '_meta'
## EDIT 2
paginator = Paginator(filteredData, rowsPerPage)
try:
data = paginator.page(page)
except PageNotAnInteger:
data = paginator.page(1)
except EmptyPage:
data = paginator.page(paginator.num_pages)
serializedData = serializers.serialize("json", data)
## NEW ERROR
Traceback (most recent call last):
File "C:\Python27\lib\site-packages\django\core\handlers\base.py", line 115, in get_response
response = callback(request, *callback_args, **callback_kwargs)
File "C:\Users\Milan\Desktop\DA_LI_RADI\Test projekat\st_forms\views.py", line 238, in getFormData
serializedData = json.dumps({'data': data})
File "C:\Python27\lib\json\__init__.py", line 243, in dumps
return _default_encoder.encode(obj)
File "C:\Python27\lib\json\encoder.py", line 207, in encode
chunks = self.iterencode(o, _one_shot=True)
File "C:\Python27\lib\json\encoder.py", line 270, in iterencode
return _iterencode(o, 0)
File "C:\Python27\lib\json\encoder.py", line 184, in default
raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <Page 1 of 1> is not JSON serializable
Answer: The problem is not the pagination, but the way you serialize your data:
`serializers.serialize` is built to serialize Django model instances (from a
list or a `QuerySet`), nothing else. You can use the `json` module from the
python stdlib to serialize 'raw' dictionaries, try for example:
import json
print json.dumps({'your': 'dict'})
You might need to convert the `ValuesQuerySet` to a vanilla list-of-dicts to
convince the `json` module to work, though:
# [...]
data = paginator.page(1)
print json.dumps(list(data))
|
Calling IDA Pro through python
Question: I am trying to use a python script to call IDA Pro and have it run in bash
mode. Similar to that of the linux terminal line './idal -B input-File' is
there a quick and simple way I can do this throughout the python script? I
have looked through the IDA Pro book and I can only find information on
IDAPython which I am struggling to understand.
Answer: This is a duplicate.
Checkout [this](http://stackoverflow.com/questions/89228/calling-an-external-
command-in-python) answer.
It's basically resumes to:
from subprocess import call
call(["./idal", "-B", "input-File"])
|
Creating an sqlite database search engine with python
Question: I have an sqlite database with 2 tables. I need to create a cgi search engine
for the database, with 2 options in a drop-down menu: Name & Keyword.
If the option is Keyword, the 1st table is searched for a matching keyword (in
any column). If the option is Name, the 1st column of the 2nd table is
searched for an exact match.
I have created the cgi web interface with a search box, and the drop-down
menu, that saves the input search term. Now I am stuck as to how I can program
my cgi script to do a search of the database based on the input term, and
display the results to screen as a table.
Below are the relevant parts of my script:
import cgi
"""set up the content type, open the html, title, and body"""
print '<form action=search.cgi>'
print '<select name=\'dropdown\'>'
print '<option> Name </option>'
print '<option> Keyword </option>'
print '</select>'
print '<input type=\'text\' name=\'desc\' size=\'25\'>'
print '<button type="submit"> Go </button>'
print '</form>'
args = cgi.FieldStorage()
desc = args.getfirst("desc")
dropdown = args.getfirst("dropdown")
And here is where I need help:
if dropdown == 'Keyword':
...
elif dropdown == 'Name':
...
Thanks in advance for any help!
Answer: It seems you just need to do some pretty basic sqlite database operations. The
[stdlib documentation](http://docs.python.org/2/library/sqlite3.html) should
get you most of the way. It has also links for more resources to help you do
more comprehensive SQL queries.
|
Python 2.7: Issues When Importing a Class
Question: I have been searching high and low for an answer and cannot seem to find one.
I am running into a fundamental issue when attempting to import a class from
another file. I am relatively new to Python and OOP in general, so forgive me
if my query is rudimentary.
**The Issue:** I want to import a CHILD class into a PARENT class. Simple
enough, but when I import the class it immediately executes.
**The Question:** How do I import a class so it can be referenced globally in
my parent class?
Here is a basic example of the PARENT class:
from child import CHILD
class PARENT:
def _init_(self):
print "START PARENT CLASS"
def goTo(self,enter):
if enter == "1":
c.childScreen()
else:
self.parentScreen(self):
def parentScreen(self):
enter = raw_input("ENTER [1] to go to CHILD class:")
self.goTo(enter)
p = PARENT()
c = CHILD()
Okay, so to my beginner eyes this conceptually should work. I imported the
class CHILD and created a reference to it "c = CHILD". This concept works when
both class's are in the same file but not when they are in two different
files. Why?
Instead of importing CHILD from child and storing it as a reference it instead
executes immediately and does not initiate the PARENT class. Why doesn't this
work?
I have seen people reference the whole '_name_ ' == '_main_ ' but I don't
really know how to implement that and I feel as if there is an easier way.
Any help would be appreciated. Thank you!
Answer: You are importing the `CHILD` class properly, but you are calling it from
outside your `PARENT` class. The `PARENT` class thinks that the variable `c`
is a local variable to the function `goTo`. You could use a global variable
`c`, but anyone would tell you that that is a big no no.
To answer your other question you probably have some code that executes in
`CHILD`. If you only want this code to run when you run the file in which the
`CHILD` class then put it after a
if __name__ == '__main__':
This only allows the code preceding it to run if executed directly and it will
not run if you import the class. see examples below.
You can just create an instance variable of the CHILD class in your `__init__`
and use it in the rest of your PARENT class.
class PARENT(object):
def _init_(self):
print "START PARENT CLASS"
self.c = CHILD() # create instance of CHILD
def goTo(self,enter):
if enter == "1":
self.c.childScreen() # then you can access CHILD class like this
else:
self.parentScreen(self):
def parentScreen(self):
enter = raw_input("ENTER [1] to go to CHILD class:")
self.goTo(enter)
if __name__ == '__main__':
p = PARENT()
or you can actaully inherit CHILD into PARENT:
class PARENT(CHILD):
def _init_(self):
print "START PARENT CLASS"
def goTo(self,enter):
if enter == "1":
# now you can access the CHILD functions as if the we were coded in the
# PARENT class
self.childScreen()
else:
self.parentScreen(self):
def parentScreen(self):
enter = raw_input("ENTER [1] to go to CHILD class:")
self.goTo(enter)
if __name__ == '__main__':
p = PARENT()
|
Python pandas find starting/ending row and rounding numbers
Question:
import pandas as pd
import numpy as np
import urllib
url = 'http://cawcr.gov.au/staff/mwheeler/maproom/RMM/RMM1RMM2.74toRealtime.txt'
urllib.urlretrieve(url,'datafile.txt')
df = pd.read_table('datafile.txt', sep='\s+', header=None)
df.columns = ['year', 'month', 'day', 'n1', 'n2', 'n3', 'n4', 'type']
df = df[df.year > 1978] #new starting row is created, how do I find what the new starting row is
df = df[df.type < 'Prelim_value'] #new ending row is created, how do I find what the new ending row is
tda1 = []
for a in range(starting_row, ending_row):
if a < starting_row+19:
tda1.append(0.0)
else:
ch = df.ix[a:a+20, ['n1']]
dc = np.round(ec,0)
tda1.append(ec)
How do I find the starting row after chopping off the beginning of the file,
ditto on finding the ending row?
Would I need to create a whole new dataframe if I wanted to keep everything
together...aka, I want to have tda1 being right in line with n1. If I access
`tda1[1700]` and `n1[1700]` I want them to both be pointing to the same date.
As of yet I still can't get `df.iloc(0)['n1']` or any other combo of to give
me anything other than an error suggesting that DataFrame object is not an
attribute of iloc.
Answer: To quickly answer your last question, use:
import numpy as np
np.round(ec, 0)
For your first (series of) question(s), you don't give us any data to play
with and your questions isn't very clear. Either way, you can always get the
the first and last rows of _any_ dataframe with `df.iloc[0]` and
`df.iloc[-1]`, respectively.
### Edits:
If you simply need to know how many rows you have, use `df.shape`. Here's a
toy example:
import pandas
df = pandas.DataFrame([
(1977, 1, 1),
(1978, 1, 2),
(1979, 1, 3),
(1980, 1, 4),
(1977, 2, 1),
(1978, 2, 2),
(1979, 2, 3),
(1980, 2, 4),
(1977, 3, 1),
(1978, 3, 2),
(1979, 3, 3),
(1980, 3, 4),
], columns=['year', 'a', 'b'])
print(df.to_string())
Which prints:
year a b
0 1977 1 1
1 1978 1 2
2 1979 1 3
3 1980 1 4
4 1977 2 1
5 1978 2 2
6 1979 2 3
7 1980 2 4
8 1977 3 1
9 1978 3 2
10 1979 3 3
11 1980 3 4
And then:
df = df[df.year > 1978]
df = df[df.a < 3]
print(df.to_string())
which gives:
year a b
2 1979 1 3
3 1980 1 4
6 1979 2 3
7 1980 2 4
Try this our yourself after executing everything above:
print(df.shape)
for row in range(df.shape[0]-1):
print(df.iloc[row])
### For rounding:
df = pandas.DataFrame(np.random.normal(size=(4,4)))
rounded = np.round(df,1)
print(rounded.to_string())
0 1 2 3
0 -1.2 1.9 0.7 -0.8
1 -0.5 0.9 1.6 -0.3
2 0.4 -0.2 -1.6 -0.2
3 -1.7 1.1 0.1 -0.6
|
python - recursively deleting dict keys?
Question: I'm using Python 2.7 with `plistlib` to import a .plist in a nested dict/array
form, then look for a particular key and delete it wherever I see it.
When it comes to the actual files we're working with in the office, I already
know where to find the values -- but I wrote my script with the idea that I
didn't, in the hopes that I wouldn't have to make changes in the future if the
file structure changes or we need to do likewise to other similar files.
Unfortunately I seem to be trying to modify a dict while iterating over it,
but I'm not certain how that's actually happening, since I'm using
`iteritems()` and `enumerate()` to get generators and work with those instead
of the object I'm actually working with.
def scrub(someobject, badvalue='_default'): ##_default isn't the real variable
"""Walks the structure of a plistlib-created dict and finds all the badvalues and viciously eliminates them.
Can optionally be passed a different key to search for."""
count = 0
try:
iterator = someobject.iteritems()
except AttributeError:
iterator = enumerate(someobject)
for key, value in iterator:
try:
scrub(value)
except:
pass
if key == badvalue:
del someobject[key]
count += 1
return "Removed {count} instances of {badvalue} from {file}.".format(count=count, badvalue=badvalue, file=file)
Unfortunately, when I run this on my test .plist file, I get the following
error:
Traceback (most recent call last):
File "formscrub.py", line 45, in <module>
scrub(loadedplist)
File "formscrub.py", line 19, in scrub
for key, value in iterator:
RuntimeError: dictionary changed size during iteration
So the problem might be the recursive call to itself, but even then shouldn't
it just be removing from the original object? I'm not sure how to avoid
recursion (or if that's the right strategy) but since it's a .plist, I do need
to be able to identify when things are dicts or lists and iterate over them in
search of either (a) more dicts to search, or (b) the actual key-value pair in
the imported .plist that I need to delete.
Ultimately, this is a _partial_ non-issue, in that the files I'll be working
with on a regular basis have a known structure. However, I was really hoping
to create something that doesn't care about the nesting or order of the object
it's working with, as long as it's a Python dict with arrays in it.
Answer: Adding or removing items to/from a sequence while iterating over this sequence
is tricky at best, and just illegal (as you just discovered) with dicts. The
right way to remove entries from a dict while iterating over it is to iterate
on a snapshot of the keys. In Python 2.x, `dict.keys()` provides such a
snapshot. So for dicts the solution is:
for key in mydict.keys():
if key == bad_value:
del mydict[key]
For lists, trying to iterate on a snapshot of the indexes (ie `for i in
len(thelist):`) would result in an IndexError as soon as anything is removed
(obviously since at least the last index will no more exist), and even if not
you might skip one or more items (since the removal of an item makes the
sequence of indexes out of sync with the list itself). `enumate` is safe
against IndexError (since the iteration will stop by itself when there's no
more 'next' item in the list, but you'll still skip items:
>>> mylist = list("aabbccddeeffgghhii")
>>> for x, v in enumerate(mylist):
... if v in "bdfh":
... del mylist[x]
>>> print mylist
['a', 'a', 'b', 'c', 'c', 'd', 'e', 'e', 'f', 'g', 'g', 'h', 'i', 'i']
Not a quite a success, as you can see.
The known solution here is to iterate on reversed indexes, ie:
>>> mylist = list("aabbccddeeffgghhii")
>>> for x in reversed(range(len(mylist))):
... if mylist[x] in "bdfh":
... del mylist[x]
>>> print mylist
['a', 'a', 'c', 'c', 'e', 'e', 'g', 'g', 'i', 'i']
This works with reversed enumeration too, but we dont really care.
So to summarize: you need two different code path for dicts and lists - and
you also need to take care of "not container" values (values which are neither
lists nor dicts), something you do not take care of in your current code.
def scrub(obj, bad="_this_is_bad"):
if isinstance(obj, dict):
for k in obj.keys():
if k == bad:
del obj[k]
else:
scrub(obj[k], bad)
elif isinstance(obj, list):
for i in reversed(range(len(obj))):
if obj[i] == bad:
del obj[i]
else:
scrub(obj[i], bad)
else:
# neither a dict nor a list, do nothing
pass
As a side note: **never** write a bare except clause. Never **ever**. This
should be illegal syntax, really.
|
Compare incomplete date list with a reference date list
Question: I know this is possible. I know there is a simple solution, but everything
I've tried has failed.
Here's the deal:
I have a dataset in Excel format containing 939,019 weather station records
(rows). The date/time interval is every 10 minutes starting from 1/29/1993
16:30 to 6/30/2013 24:00. If I do the math, it is clear that there are missing
rows.
I need to know the missing dates/times. It would be cool if I could have some
little program/script that returned the start date/time and end date/time of
the missing intervals. But I'll just be happy with a list of the missing
dates/times.
To figure it out, I thought, oh, all I need is a reference list to compare the
list with missing dates and have some way of flagging or returning the gaps.
So, in Excel, I created a column adjacent to the weather station data and
populated the first row with the start date. The subsequent rows just add 10
minutes to the cell above it. Unfortunately, the number of 10 minute intervals
in that 20 year span is more than excel can handle. No worries. It gets close
enough (1/6/2013 10:50).
Anyway, I tried the MATCH function in excel, but that is taking way too long.
In the time it is taking me to type this, it has reached 3% (using 12
processors). I have 30 weather stations (with the same date range) to do. I'm
hoping I can find a faster way to do this.
So, I next tried Acess. I imported the files (the weather station data and a
separate reference date list) as tables in Access and thought I'd just do an
UNMATCHED query, but for some reason (no matter how I format the date column
(date/time, serial number), the query returns just about all the rows as
unmatched. Not sure why, and it does do it quick, but it is obviously wrong.
I then thought - Python! That'd do it, right? But I'm a GIS person. I've only
ever used Python sample scripts to run geoprocessing tools (or used ESRi's
Model Builder). I don't really have a clue where to start. Any pointers?
Answer: First, check out [python-excel.org](http://www.python-excel.org/) for `xlrd`,
`xlwt`, and `xlutils` modules and documentation (I'm assuming you're working
with `.xls` files, and not `.xlsx` \- if so, check out
[`openpyxl`](http://pythonhosted.org/openpyxl/)). Once you've got them
installed, read through the docs to familiarize yourself with them, they're
not too long or overly complicated. The actual comparison shouldn't be too
hard: all you need to do is read cell N, compare its value to cell N+1, and
see if the difference is 10 minutes. If it is, great, go to the next value. If
not, print the value to a new workbook (or whatever you want to do - insert a
blank row with the missing time and calculate again, or what have you).
I don't know how long this will take to run through ~30 million records, but
I'm willing to bet it'll be faster than doing it via Excel itself :)
Good luck!
|
Summing one array in terms of another - python
Question: I have two corresponding 2D arrays, one of velocity, one of intensity. The
values of intensity match each of the velocity elements.
I have created another 1d array that that goes from min to max velocity in
even bin widths.
How would I sum the intensity values from my 2d array which correspond to my
velocity bins in my 1d array.
For example: if I have I = 5 corresponding to velocity = 101km/s, then this is
added to the bin 100 - 105 km/s.
Here's my input:
rad = np.linspace(0, 3, 100) # polar coordinates
phi = np.linspace(0, np.pi, 100)
r, theta = np.meshgrid(rad, phi) # 2d arrays of r and theta coordinates
V0 = 225 # Velocity function w/ constants.
rpe = 0.149
alpha = 0.003
Vr = V0 * (1 - np.exp(-r / rpe)) * (1 + (alpha * np.abs(r) / rpe)) # returns 100x100 array of Velocities.
Vlos = Vr * np.cos(theta)# Line of sight velocity assuming the observer is in the plane of the polar disk.
a = (r**2) # intensity as a function of radius
b = (r**2 / 0.23)
I = (3.* np.exp(-1. * a)) - (1.8 * np.exp(-1. * b))
I wish to first create velocity bins from Vmin to Vmax and then sum the
intensities over each bin.
My desired out put would be something along the lines of
V_bins = [0, 5, 10,... Vlos.max()]
I_sum = [1.4, 1.1, 1.8, ... 1.2]
plot(V_bins, I_sum)
EDIT: I have come up with temporary solution but perhaps there is a more
elegant/efficient method of achieving it?
The two array Vlos and I are both 100 by 100 matrices.
Vlos = array([[ 0., 8.9, 17.44, ..., 238.5],...,
[-0., -8.9, -17.44, ..., -238.5]])
I = random.random((100, 100))
V = np.arange(Vlos.min(), Vlos.max()+5, 5)
bins = np.zeros(len(V))
for i in range(0, len(V)-1):
for j in range(0, len(Vlos)): # horizontal coordinate in matrix
for k in range(0, len(Vlos[0])): # vert coordinate
if Vlos[j,k] >= V[i]and Vlos[j,k] < V[i+1]:
bins[i] = bins[i] + I[j,k]
The result is plotted below. The overall shape in the histogram is to be
expected, however I don't understand the spike in the curve at V = 0. As far
as I can tell this isn't there in the data which leads me to question my
method.
Any further help would be appreciated.
Answer:
import numpy as np
bins = np.arange(100,120,5)
velocities = np.array([101, 111, 102, 112])
intensities = np.array([1,2,3,4])
h = np.histogram(velocities, bins, weights=intensities)
print h
Output:
(array([4, 0, 6]), array([100, 105, 110, 115]))
|
How to skip the unmodified modules importing in PYTHON
Question: I have a lot of modules to import before running each script. But the modules
i am importing is same in all the scripts. In case of debugging i have to
change some code in one or more modules and again run the script. So each time
python imports all the modules from the starting. Is there anyway that i skip
importing of modules that haven't modified?
Answer: You can reload particular modules with
[`reload`](http://docs.python.org/2/library/functions.html#reload) function,
like this
reload(math)
|
Python debugging, stop at particular output
Question: I have complex python project with lots of modules, loggers, twisted defereds
and other stuff.
And somewhere in the code some line is printed to logs, and I want to find out
where. Usually I just search the codebase for that string, but now that string
is generated dynamically, so is not searchable.
And I wander if there is any way to run python in some debug mode, and tell it
to stop when some pattern will appear in sdout, and then print location in
code where it stopped?
Answer: How about replacing `sys.stdout`?
For example:
import sys
import traceback
class StacktraceOnPrint:
def __init__(self, orig_stdout, substring):
self.orig_stdout = orig_stdout
self.substring = substring
def write(self, txt):
if self.substring in txt:
traceback.print_stack() # OR import pdb; pdb.set_trace()
self.orig_stdout.write(txt)
sys.stdout = StacktraceOnPrint(sys.stdout, 'blah')
print 'test ...'
print 'Hello blah.'
print 'test ...'
**NOTE**
[`traceback.print_stack`](http://docs.python.org/2/library/traceback.html#traceback.print_stack)
uses `sys.stderr`. If you want to catch `sys.stderr`, use different function
(like
[`traceback.format_stack`](http://docs.python.org/2/library/traceback.html#traceback.format_stack)).
Otherwise it recurses forever; causes `RuntimeError: maximum recursion depth
exceeded` ..
|
Looking for a quick way to speed up my code
Question: I am looking for a way to speed up my code. I managed to speed up most parts
of my code, reducing runtime to about 10 hours, but it's still not fast enough
and since I'm running out of time I'm looking for a quick way to optimize my
code.
**An example:**
text = pd.read_csv(os.path.join(dir,"text.csv"),chunksize = 5000)
new_text = [np.array(chunk)[:,2] for chunk in text]
new_text = list(itertools.chain.from_iterable(new_text))
In the code above I read in about 6 million rows of text documents in chunks
and flatten them. This code takes about 3-4 hours to execute. This is the main
bottleneck of my program. **edit** : I realized that I wasn't very clear on
what the main issue was, **The flattening is the part which takes the most
amount of time.**
Also this part of my program takes a long time:
train_dict = dict(izip(text,labels))
result = [train_dict[test[sample]] if test[sample] in train_dict else predictions[sample] for sample in xrange(len(predictions))]
The code above first zips the text documents with their corresponding labels
(This a machine learning task, with the train_dict being the training set).
Earlier in the program I generated predictions on a test set. There are
duplicates between my train and test set so I need to find those duplicates.
Therefore, I need to iterate over my test set row by row (2 million rows in
total), when I find a duplicate I actually don't want to use the predicted
label, but the label from the duplicate in the train_dict. I assign the result
of this iteration to the variable result in the above code.
I heard there are various libraries in python that could speed up parts of
your code, but I don't know which of those could do the job and right know I
do not have the time to investigate this, that is why I need someone to point
me in the right direction. Is there a way with which I could speed the code
snippets above up?
**edit2**
I have investigated again. And it is definitely a memory issue. I tried to
read the file in a row by row manner and after a while the speed declined
dramatically, furthermore my ram usage is nearly 100%, and python's disk usage
increased sharply. How can I decrease the memory footprint? Or should I find a
way to make sure that I don't hold everything into memory?
**edit3** As memory is the main issue of my problems I'll give an outline of a
part of my program. I have dropped the predictions for the time being, which
reduced the complexity of my program significantly, instead I insert a
standard sample for every non duplicate in my test set.
import numpy as np
import pandas as pd
import itertools
import os
train = pd.read_csv(os.path.join(dir,"Train.csv"),chunksize = 5000)
train_2 = pd.read_csv(os.path.join(dir,"Train.csv"),chunksize = 5000)
test = pd.read_csv(os.path.join(dir,"Test.csv"), chunksize = 80000)
sample = list(np.array(pd.read_csv(os.path.join(dir,"Samples.csv"))[:,2]))#this file is only 70mb
sample = sample[1]
test_set = [np.array(chunk)[:,2] for chunk in test]
test_set = list(itertools.chain.from_iterable(test_set))
train_set = [np.array(chunk)[:,2] for chunk in train]
train_set = list(itertools.chain.from_iterable(train_set))
labels = [np.array(chunk)[:,3] for chunk in train_2]
labels = list(itertools.chain.from_iterable(labels))
"""zipping train and labels"""
train_dict = dict(izip(train,labels))
"""finding duplicates"""
results = [train_dict[test[item]] if test[item] in train_dict else sample for item in xrange(len(test))]
Although this isn't my entire program, this is the part of my code that needs
optimization. As you can see I am only using three important modules in this
part, pandas, numpy and itertools. The memory issues arise when flattening
train_set and test_set. The only thing I am doing is reading in the files,
getting the necessary parts zipping the train documents with the corresponding
labels in a dictionary. And then search for duplicates.
**edit 4** As requested I'll give an explanation of my data sets. My Train.csv
contains 4 columns. The first columns contain ID's for every sample, the
second column contains titles and the third column contains text body
samples(varying from 100-700 words). The fourth column contains category
labels. Test.csv contains only the ID's and text bodies and titles. The
columns are separated by commas.
Answer: You can try [Cython](http://cython.org/). It supports numpy and can give you a
nice speedup. Here is an introduction and explanation of what needs to be done
<http://www.youtube.com/watch?v=Iw9-GckD-gQ>
|
Simple loading time series and plot in python
Question: Being a beginner with python, I am very frustrated because after hours of
research I can not find a solution for reading+plotting time serieses in
python which could be done in matlab, R or gnuplot in 1 minute.
Data file:
# id date value1 quality anothervalue value2
1 2011-05-19_16:30:19 974.3 3_1x NODATA 10E-4
...
I tried this:
import pandas as pd
import numpy as np
from pandas import Series, DataFrame, Panel
import matplotlib as mp
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
a,b,c,d,e,f = np.loadtxt("dataset.dat", unpack=True,
converters={ 1: mdates.strpdate2num('%Y-%m-%d_%H:%M:%S') })
plt.plot_date(x=b, y=c)
plt.show()
Python keeps failing because it tries to automatically convert the data into
float. So I tried to use the converters, but it fails for the other columns.
No plot at all.
* how do I tell python to ignore lines beginning with # ?
* do i have to convert everything by hand or can i just read in a dataset without conversion?
* how to finally plot value1 over datetime?
* can I tell python to interpret NODATA as a value without data? So it does not plot it?
Is python so badly documented that one could not google a solution after hours
or did I just miss something really practically useful out there?
Answer: Not sure if you can achieve desired result with numpy, as it's not well suited
for arrays of different types. But as you import pandas, you can use
`pd.read_csv`:
>>> from StringIO import StringIO
>>> s = """# id date value1 quality anothervalue value2
... 1 2011-05-19_16:30:19 974.3 3_1x NODATA 10E-4"""
>>> pd.read_csv(StringIO(s[2:]), sep='\s+',
... date_parser=mdates.strpdate2num('%Y-%m-%d_%H:%M:%S'),
... parse_dates=['date'])
id date value1 quality anothervalue value2
0 1 734276.68772 974.3 3_1x NODATA 0
|
Java Run Static Method in New Thread
Question: I just started learning java and I ran into a slight road block involving
threads. I have a static method that I would like to run in its own thread, is
this possible? In python I know it would look something like this: `import
thread;thread.start_new_thread( my_function, () );` And I know how to use
threading with non-static methods by implementing Runnable or extending
thread, but this is not what I am trying to do.
Answer: Have a `Thread`'s `run` method call the `static` method:
new Thread(new Runnable() {
public void run() {
Call.yourStaticMethod();
}
}).start();
|
Is there a method like append for dictionaries
Question: How do i add key,value to a dictionary in python? I defined an empty
dictionary and now I want to pass a bunch of keys from a list and set their
value as 1. From what I did it creates me every iteration a new dictionary,
but I want to append the key,value so eventually I will recieve only one
dictionary. this is my code:
def count_d(words):
count_dict={}
words_set= set(words)
for i in words_set:
count_dict[i]= 1
print (count_dict)
Answer: What you are looking for is
[dict.fromkeys](http://docs.python.org/2/library/stdtypes.html#dict.fromkeys)
along with
[dict.update](http://docs.python.org/2/library/stdtypes.html#dict.update).
**From the docs**
> Create a new dictionary with keys from seq and values set to value.
**Example Usage**
>>> d = {}
>>> d.update(dict.fromkeys(range(10), 1))
>>> d
{0: 1, 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1}
Note, you need an `dict.update` along with `dict.fromkeys`, so as to update
the dictionary in-place
Instead, if you want to create a dictionary and assign use the notation
>>> d = dict.fromkeys(range(10), 1)
>>> d
{0: 1, 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1}
Unfortunately, for in-place update, you need to create a throw-away dictionary
before passing to the `dict.update` method. A non-intuitive method is to
leverage [itertools](http://docs.python.org/2/library/itertools.html)
from itertools import izip, repeat
d.update(izip(xrange(10), repeat(1)))
The same idea can be extended to
[OrderedDict](http://docs.python.org/2/library/collections.html#collections.OrderedDict)
which is often used, as an alternate for `OrderedSet` as standard library does
not provide one.
|
Python solution for reading a text file into an if statement
Question: I am a new to Python and I am trying to parse some network data to figure out
where a certain ip address is based on the city that it is in. I have the
following code working below. But I have several hundred lines of information
that I would like my script to go through and creating a specific if/else
statement for each one didn't seem efficient.
from netaddr import *
def locateip(ipaddr):
if IPAddress(ipaddr) in IPNetwork('10.10.10.0/24'):
return 'New York', '10', '10.10.10.0', '10.10.10.0/24', '255.255.255.0'
elif IPAddress(ipaddr) in IPNetwork('10.10.20.0/24'):
return 'Chicago', '20', '10.10.20.0', '10.10.20.0/24', '255.255.255.0'
elif IPAddress(ipaddr) in IPNetwork('10.10.20.0/24'):
return 'Dallas', '30', '10.10.30.0', '10.10.30.0/24', '255.255.255.0'
ipaddrsource = raw_input('Source Ip Address:')
try:
srclocation, srcvlan, srcnetwork, srcnetworkcidr, srcsubnetmask = locateip(ipaddrsource)
except Exception, e:
print e
print 'Location: ' + str(srclocation)
print 'Vlan: ' + str(srcvlan)
print 'Network: ' + str(srcnetwork)
print 'Network/CIDR: ' + str(srcnetworkcidr)
print 'Subnet Mask: ' + str(srcsubnetmask)
All my data is formatted into a text file similar to what is listed below.
location vlan network network+cidr subnetmask
New York 10 10.10.10.0 10.10.10.0/24 255.255.255.0
Chicago 20 10.10.20.0 10.10.20.0/24 255.255.255.0
Dallas 30 10.10.30.0 10.10.30.0/24 255.255.255.0
I have been trying to get the following to work, but I haven't been able to
figure out how to send a line out of a text file into the if statement to
return the rest of the metadata back. Any help would be great!
from netaddr import *
def locateip(ipaddr):
f = open('networkinfo.txt','r')
for line in f:
networkdata = line.split()
if IPAddress(ipaddr) in IPNetwork(networkdata[3]):
return networkdata[0], networkdata[1], networkdata[2], networkdata[3], networkdata[4]
ipaddrsource = raw_input('Source Ip Address:')
try:
srclocation, srcvlan, srcnetwork, srcnetworkcidr, srcsubnetmask = locateip(ipaddrsource)
except Exception, e:
print e
print 'Location: ' + str(srclocation)
print 'Vlan: ' + str(srcvlan)
print 'Network: ' + str(srcnetwork)
print 'Network/CIDR: ' + str(srcnetworkcidr)
print 'Subnet Mask: ' + str(srcsubnetmask)
Answer: Your lines start with a location, which itself can contain spaces. As such a
straightforward `str.split()` won't work:
>>> 'New York 10 10.10.10.0 10.10.10.0/24 255.255.255.0\n'.split()
['New', 'York', '10', '10.10.10.0', '10.10.10.0/24', '255.255.255.0']
Note how `New` and `York` are two separate entries here, making
`networkdata[3]` the wrong entry.
You need to split from the end, and limit the number of splits:
networkdata = line.rsplit(None, 4)
Demo:
>>> 'New York 10 10.10.10.0 10.10.10.0/24 255.255.255.0\n'.rsplit(None, 4)
['New York', '10', '10.10.10.0', '10.10.10.0/24', '255.255.255.0']
where `None` still splits on arbitrary-width whitespace and strips the newline
from the end, but the `4` limits the splitting to 4 separators, leaving `New
York` intact.
Or, as a complete method with some small improvements:
def locateip(ipaddr):
ipaddr = IPAddress(ipaddress)
with open('networkinfo.txt') as f:
next(f, None) # skip the header line first
for line in f:
location, vlan, net, netcdr, mask = line.rsplit(None, 4)
if ipaddr in IPNetwork(netcdr):
return location, vlan, net, netcdr, mask
It _could_ be that your input format is actually using tabs instead:
New York\t10\t10.10.10.0\t10.10.10.0/24\t255.255.255.0
in which case you probably want to read the format with the `csv` module
instead:
import csv
def locateip(ipaddr):
ipaddr = IPAddress(ipaddress)
with open('networkinfo.txt') as f:
reader = csv.reader(f, delimiter='\t')
next(reader, None) # skip the header line first
for location, vlan, net, netcdr, mask in reader:
if ipaddr in IPNetwork(netcdr):
return location, vlan, net, netcdr, mask
|
Python: arguments - 4 arguments allowed, 5 given
Question: Trying to create a matrix to start a search algorithm.
from numpy import *
z11 = vars()
z12 = vars()
z13 = vars()
z14 = vars()
z21 = vars()
z22 = vars()
z23 = vars()
z24 = vars()
z31 = vars()
z32 = vars()
z33 = vars()
z34 = vars()
z41 = vars()
z42 = vars()
z43 = vars()
z44 = vars()
A = matrix([z11,z12,z13,z14], [z21,z22,z23,z24], [z31,z32,z33,z34], [z41,z42,z43,z44])
When it is run for errors, it comes up with:
Traceback (most recent call last):
File "Fusion Puzzle Algorithm 2.py", line 20, in <module>
A = matrix([z11,z12,z13,z14], [z21,z22,z23,z24], [z31,z32,z33,z34], [z41,z42,z43,z44])
TypeError: __new__() takes at most 4 arguments (5 given)
How can I get this to work?
Answer: You likely want something like:
A = matrix([[z11,z12,z13,z14], [z21,z22,z23,z24], [z31,z32,z33,z34], [z41,z42,z43,z44]])
Note that there is only one argument to the matrix constructor.
|
NLTK set method prints characters, not words
Question: I'm new to NLTK (and python...) and I'm having two issues with one of its
basic methods: when I call
sorted(set(<one of nltk's preloaded corpora>))
it prints a list of all the words in the text, but each word is preceded by
'u', like so: [u'yourselves', u'youth']. I thought I'd broken the tokenizer,
but I tried re-cloning the repo and re-installing.
The second, possibly related issue is that when I define a try using those
methods on a string I pass in myself, I get the individual characters, rather
than the words. Do I need to parse text that I pass in prior to using set()?
Answer: **`u'foo bar'`** is a just a string in `unicode`. both `str` and `unicode` are
considered as `basestring` (see <http://docs.python.org/2/howto/unicode.html>,
<http://docs.python.org/2/library/functions.html#basestring>)
>>> x = u'foobar'
>>> isinstance(x, str)
False
>>> isinstance(x,unicode)
True
>>> isinstance(x,basestring)
True
>>> print x
foobar
When you try to access a corpus from NLTK's corpus readers, the default data
structure is a list of sentences where each sentence is a list of tokens and
each token is a basestring.
>>> from nltk.corpus import brown
>>> print brown.sents()
[['The', 'Fulton', 'County', 'Grand', 'Jury', 'said', 'Friday', 'an', 'investigation', 'of', "Atlanta's", 'recent', 'primary', 'election', 'produced', '``', 'no', 'evidence', "''", 'that', 'any', 'irregularities', 'took', 'place', '.'], ['The', 'jury', 'further', 'said', 'in', 'term-end', 'presentments', 'that', 'the', 'City', 'Executive', 'Committee', ',', 'which', 'had', 'over-all', 'charge', 'of', 'the', 'election', ',', '``', 'deserves', 'the', 'praise', 'and', 'thanks', 'of', 'the', 'City', 'of', 'Atlanta', "''", 'for', 'the', 'manner', 'in', 'which', 'the', 'election', 'was', 'conducted', '.'], ...]
If you want a plain text version of the corpus, you can simply do:
>>> for i in brown.sents():
... print " ".join(i)
... break
...
The Fulton County Grand Jury said Friday an investigation of Atlanta's recent primary election produced `` no evidence '' that any irregularities took place .
There are many internal magics in NLTK that makes the corpora work as it is
from the NLTK's modules but the simplest way to know what's in one of these
'preloaded' corpora (or more accurately 'precoded' corpus readers) is to use:
>>> dir(brown)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_add', '_c2f', '_delimiter', '_encoding', '_f2c', '_file', '_fileids', '_get_root', '_init', '_map', '_para_block_reader', '_pattern', '_resolve', '_root', '_sent_tokenizer', '_sep', '_tag_mapping_function', '_word_tokenizer', 'abspath', 'abspaths', 'categories', 'encoding', 'fileids', 'open', 'paras', 'raw', 'readme', 'root', 'sents', 'tagged_paras', 'tagged_sents', 'tagged_words', 'words']
|
Python numba.jit types
Question: I have been trying to deduce how the types are set from the numba
documentation all day. I have gotten a bit of the way, but now I want to make
a function which returns a one-dimensional array, and a two-dimensjonal array,
and take a bunch of args, and I struggle to get any further:
@jit
class name(object)
@double[:,:], double[:](double[:], double, double, int64)
def solve(self, u0, a, b, n):
self.t = linspace(a, b, n+1)
dt = abs((b-a)/float(n))
u = zeros(n+1, len([u0]))
u[0] = u0
u = advance(u, t, n, dt)
return u.transpose(), t.transpose()
The above throws these exceptions:
Traceback (most recent call last):
File "/home/marius/dev/python/inf1100/test_ODE.py", line 2, in <module>
from DE import *
File "/home/marius/dev/python/inf1100/DE.py", line 13
@double[:,:], double[:](double[:], double, double, int64)
^
SyntaxError: invalid syntax
It would be good if you could tell me what is going wrong, however it would be
even better if you could recommend a document which rigorously explains these
syntaxes once and for all.
Thank you for your time.
Kind regards, Marius
Answer: Here is a simpler version of a method that returns a tuple. This works for me
using Numba 0.11.1 on OS X:
import numba
import numpy as np
@numba.jit
class name(object):
@numba.object_(numba.double[:], numba.double)
def solve(self, x, a):
y = np.empty(x.shape[0], dtype=np.float64)
z = np.empty(x.shape[0], dtype=np.float64)
for k in xrange(x.shape[0]):
y[k] = x[k] * a
z[k] = x[k] + a
return y, z
Then using it:
C = name()
a, b = C.solve(np.arange(5, dtype=np.float64), 3.0)
Where `a` and `b` are:
In [24]: a
Out[24]:
array([ 0., 3., 6., 9., 12.])
In [22]: b
Out[22]:
array([ 3., 4., 5., 6., 7.])
|
urllib.request for python 3.3 not working to download file
Question: I would like to download a large archive file with python and save it, but
urllib is not working for me. This is my code:
import urllib
urllib.request("http://www.petercollingridge.co.uk/sites/files/peter/particle_tutorial_7.txt")
Note that the link I used in this example is not a large archive. I am only
using it as an example. It links directly to a .txt file, so it should work. I
am getting this error:
Traceback (most recent call last):
File "<pyshell#11>", line 1, in <module>
urllib.request("http://www.petercollingridge.co.uk/sites/files/peter/particle_tutorial_7.txt")
AttributeError: 'module' object has no attribute 'request'
It seems to me like urllib is somehow broken and missing the "request" method.
I am using Python 3.3. Should I be using another module or is it actually a
Python problem?
Answer: No, it is not broken. [The `urllib.request`
documentation](http://docs.python.org/3.3/library/urllib.request.html) is
pretty clear on how this works:
import urllib.request
req = urllib.request.urlopen('http://www.google.com')
data = req.read()
**Edit:** If you need to write the file directly to disk rather than process
the data, use `urlretrieve`.
urllib.request.urlretrieve('http://example.com/big.zip', 'file/on/disk.zip')
|
Find + Find next in Python
Question: Let L be a list of strings.
Here is the code I use for finding a string `texttofind` in the list L.
texttofind = 'Bonjour'
for s in L:
if texttofind in s:
print 'Found!'
print s
break
How would you do a **Find next** feature ? Do I need to store the index of the
previously found string?
Answer: One approach for huge lists would be to use a generator. Suppose you do not
know whether the user will need the next match.
def string_in_list(s, entities):
"""Return elements of entities that contain given string."""
for e in entities:
if s in e:
yield e
huge_list = ['you', 'say', 'hello', 'I', 'say', 'goodbye'] # ...
matches = string_in_list('y', huge_list) # look for strings with letter 'y'
next(matches) # first match
next(matches) # second match
The other answers suggesting list comprehensions are great for short lists
when you want all results immediately. The nice thing about this approach is
that if you never need the third result no time is wasted finding it. Again,
it would really only matter for big lists.
**Update:** If you want the cycle to restart at the first match, you could do
something like this...
def string_in_list(s, entities):
idx = 0
while idx < len(entities):
if s in entities[idx]:
yield entities[idx]
idx += 1
if idx >= len(entities):
# restart from the beginning
idx = 0
huge_list = ['you', 'say', 'hello']
m = string_in_list('y', huge_list)
next(m) # you
next(m) # say
next(m) # you, again
See [How to make a repeating
generator](http://stackoverflow.com/questions/1376438/how-to-make-a-repeating-
generator-in-python) for other ideas.
**Another Update**
It's been years since I first wrote this. Here's a better approach using
[`itertools.cycle`](https://docs.python.org/3.5/library/itertools.html#itertools.cycle):
from itertools import cycle # will repeat after end
# look for s in items of huge_list
matches = cycle(i for i in huge_list if s in i)
next(matches)
|
How to use Hg-to-Git tool - fast-export?
Question: I have tried the instructions from this [SO
post](http://stackoverflow.com/questions/16037787/convert-mercurial-project-
to-git):
cd ~
git clone git://repo.or.cz/fast-export.git
git init git_repo
cd git_repo
~/fast-export/hg-fast-export.sh -r /path/to/old/mercurial_repo
git checkout HEAD
However when doing `git checkout HEAD` it throws:
error: pathspec 'HEAD' did not match any file(s) known to git
What is the work-around for this?
**Update:**
I managed to install mercurial-python howen when I try to import still it
would not work, the error is:
Error: No --marks option given
When doing:
C:\fast-export\hg-fast-export.py -r C:\path\to\repo
Answer: Try running `hg-fast-export.sh` instead of `hg-fast-export.py`. It looks like
the shell wrapper includes an option for `--marks` for you.
|
Python script to collect all hostnames of ip addresses with only prime entities
Question: I have a Python script to collect hostnames of ip address with primes as byte
entities. E.g., 211.13.17.2 is a valid ip according to my problem set where
every byte entity(decimal representation) is a prime.
**Code:**
from itertools import product
import socket
# prime or not
def prime(n):
if n > 1:
p = 0
for i in range(2, n-1):
if divmod(n, i)[1] == 0:
p = 1
break
if p == 0:
return True
def get_host_name(b1, b2, b3, b4):
addr = str(b1) + '.' + str(b2) + '.' + str(b3) + '.' + str(b4)
try:
return socket.gethostbyaddr(addr)
except socket.herror:
pass
# find host names whose ip addresses are all primes
byte = [b for b in range(0, 256) if prime(b)]
ips = list(product(byte, byte, byte, byte))
print 'Total ips = ', len(ips)
for ip in ips:
if get_host_name(*ip):
print get_host_name(*ip)
The problem is my script is too slow. I need expert help to optimize this
code. Please pinpoint all mistakes and ways to make it behave faster.
Answer: for the prime numbers, you can use something like this,
import numpy as np
isprime = lambda x: np.all(np.mod(x, range(2, 1 + int(np.sqrt(x)))))
primes = np.array([ x for x in range(2, 255) if isprime(x) ])
and you can have a generator for ip addresses by
('{}.{}.{}.{}'.format(*x) for x in itertools.product(primes, repeat=4))
but most likely the code is slow in the `socket` part, and because of the
number of combinations that it needs to check; for that you may _try_
parallelism, by using a pool of worker processes; something like this:
from multiprocessing import Pool
from socket import gethostbyaddr
def gethost(addr):
try:
return gethostbyaddr(addr)
except:
pass
if __name__ == '__main__':
p = Pool(3)
print (p.map(gethost,['74.125.228.137',
'11.222.333.444',
'17.149.160.49',
'98.139.183.24']))
**edit** : for only prime numbers less than 50, (50K+ combinations) and 20
worker processes it takes almost 6 minutes on my machines and it finds 16K+
results. so, with this huge number of combinations parallelism cannot help
much.
|
How to re-implement Ui_MainWindow generated by Qt
Question: I've created a interface in Qt as .ui file and then converted it to a python
file. Then, I wanted to add some functionality to the components such as radio
button, etc. For doing so, I tried to re-implement the class from Qt and add
my events. But it gives the following error:
self.radioButton_2.toggled.connect(self.radioButton2Clicked)
NameError: name 'self' is not defined
My first question is whether this is the correct/proper way to deal with
classes generated by Qt? And second, why do I get the error?
My code is here:
import sys
from PySide import QtCore, QtGui
from InterfaceClass_Test01 import Ui_MainWindow
class MainInterface(QtGui.QMainWindow, Ui_MainWindow):
def __init__(self, parent=None):
super(MainInterface, self).__init__(parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
def setupUi(self, MainWindow):
super(MainInterface, self).setupUi(parent, MainWindow)
self.radioButton.toggled.connect(self.radioButtonClicked)
self.radioButton_2.toggled.connect(self.radioButton2Clicked)
self.radioButton_3.toggled.connect(self.radioButton3Clicked)
def radioButton3Clicked(self, enabled):
pass
def radioButton2Clicked(self, enabled):
pass
def radioButtonClicked(self, enabled):
pass
Answer: The generated files are a little unintuitive. The UI class is just a simple
wrapper, and is not a sub-class of your top-level widget from Qt Designer (as
you might expect).
Instead, the UI class has a `setupUi` method that takes an instance of your
top-level class. This method will add all the widgets from Qt Designer and
make them attributes of the passed in instance (which would normally be
`self`). The attribute names are taken from the `objectName` property in Qt
Designer. It is a good idea to reset the default names given by Qt to more
readable ones so that they are easy to refer to later. (And don't forget to
re-generate the UI module after you've made your changes!)
The module that imports the UI should end up looking like this:
import sys
from PySide import QtCore, QtGui
from InterfaceClass_Test01 import Ui_MainWindow
class MainInterface(QtGui.QMainWindow, Ui_MainWindow):
def __init__(self, parent=None):
super(MainInterface, self).__init__(parent)
# inherited from Ui_MainWindow
self.setupUi(self)
self.radioButton.toggled.connect(self.radioButtonClicked)
self.radioButton_2.toggled.connect(self.radioButton2Clicked)
self.radioButton_3.toggled.connect(self.radioButton3Clicked)
def radioButton3Clicked(self, enabled):
pass
def radioButton2Clicked(self, enabled):
pass
def radioButtonClicked(self, enabled):
pass
|
Can Python read from a Windows Powershell namedpipe?
Question: I have the following named pipe created in Windows Powershell.
# .NET 3.5 is required to use the System.IO.Pipes namespace
[reflection.Assembly]::LoadWithPartialName("system.core") | Out-Null
$pipeName = "pipename"
$pipeDir = [System.IO.Pipes.PipeDirection]::InOut
$pipe = New-Object system.IO.Pipes.NamedPipeServerStream( $pipeName, $pipeDir )
Now, what i need is some Python code snippet to read from the above named pipe
created. Can Python do that ?
Thanks in advance !
Answer: Courtesy :<http://jonathonreinhart.blogspot.com/2012/12/named-pipes-between-c-
and-python.html>
Here's the C# Code
using System;
using System.IO;
using System.IO.Pipes;
using System.Text;
class PipeServer
{
static void Main()
{
var server = new NamedPipeServerStream("NPtest");
Console.WriteLine("Waiting for connection...");
server.WaitForConnection();
Console.WriteLine("Connected.");
var br = new BinaryReader(server);
var bw = new BinaryWriter(server);
while (true)
{
try
{
var len = (int)br.ReadUInt32(); // Read string length
var str = new string(br.ReadChars(len)); // Read string
Console.WriteLine("Read: \"{0}\"", str);
//str = new string(str.Reverse().ToArray()); // Aravind's edit: since Reverse() is not working, might require some import. Felt it as irrelevant
var buf = Encoding.ASCII.GetBytes(str); // Get ASCII byte array
bw.Write((uint)buf.Length); // Write string length
bw.Write(buf); // Write string
Console.WriteLine("Wrote: \"{0}\"", str);
}
catch (EndOfStreamException)
{
break; // When client disconnects
}
}
}
}
And here's the Python code:
import time
import struct
f = open(r'\\.\pipe\NPtest', 'r+b', 0)
i = 1
while True:
s = 'Message[{0}]'.format(i)
i += 1
f.write(struct.pack('I', len(s)) + s) # Write str length and str
f.seek(0) # EDIT: This is also necessary
print 'Wrote:', s
n = struct.unpack('I', f.read(4))[0] # Read str length
s = f.read(n) # Read str
f.seek(0) # Important!!!
print 'Read:', s
time.sleep(2)
Convert the C# code into a .ps1 file.
|
Logging into Stack Overflow with Mechanize and Python
Question: I have been using this guide to help me:
<http://www.pythonforbeginners.com/cheatsheet/python-mechanize-cheat-sheet/>
I want to log into Stack Overflow and print out my login response using
Mechanize in Python. I have been troubleshooting to find a form name to select
and enter my information into, but am currently getting an error "ValueError:
at least one argument must be supplied to specify control" because I am trying
to print out all forms and controls to help me figure out what I need to
choose from.
import mechanize
#make browser object
browser = mechanize.Browser()
#open stack login page
browser.open("http://stackoverflow.com/users/login#login-in")
#print all the forms on the page
print("\n Printing all forms on page...\n")
for form in browser.forms():
print("Form Name:", form.name)
print form
print("\n Done printing forms...\n")
#printing the controls of each form
browser.form=list(browser.forms())[0]
print("\n Printing controls of form 0 \n")
for control in browser.form.controls:
print control
print "type=%s, name=%s, value=%s" % (control.type, control.name, browser[control.name])
browser.form=list(browser.forms())[1]
print("\n Printing controls of form 1 \n")
for control in browser.form.controls:
print control
print "type=%s, name=%s, value=%s" % (control.type, control.name, browser[control.name])
browser.form=list(browser.forms())[2]
print("\n Printing controls of form 2 \n")
for control in browser.form.controls:
print control
print "type=%s, name=%s, value=%s" % (control.type, control.name, browser[control.name])
print("\n Done printing all controls \n")
It looks like there are 3 forms on the page, but they do not contain the email
and password inputs I am looking for to login. What am I doing wrong?
Answer: Login forms for SO appear to use extensive JavaScript. Note that all of the
buttons related to login on the page you posted call JavaScript functions.
`mechanize` can not execute JavaScript and therefore won't show the content
you need.
You could drive a browser using [Selenium](http://www.seleniumhq.org/) with
[Python bindings](https://pypi.python.org/pypi/selenium). You could also
switch to doing everything in JavaScript using
[CasperJS](http://casperjs.org/).
|
Python - Importing strings into a list, into another list :)
Question: Basically I want to read strings from a text file, put them in lists three by
three, and then put all those three by three lists into another list. Actually
let me explain it better :)
Text file (just an example, I can structure it however I want):
party
sleep
study
--------
party
sleep
sleep
-----
study
sleep
party
---------
etc
From this, I want Python to create a list that looks like this:
List1 = [['party','sleep','study'],['party','sleep','sleep'],['study','sleep','party']etc]
But it's super hard. I was experimenting with something like:
test2 = open('test2.txt','r')
List=[]
for line in 'test2.txt':
a = test2.readline()
a = a.replace("\n","")
List.append(a)
print(List)
But this just does horrible horrible things. How to achieve this?
Answer: **If you want to group the data in size of 3**. Assumes your data in the text
file is not grouped by any separator.
You need to read the file, sequentially and create a list. To group it you can
use any of the known [grouper
algorithms](http://stackoverflow.com/questions/312443/how-do-you-split-a-list-
into-evenly-sized-chunks-in-python)
from itertools import izip, imap
with open("test.txt") as fin:
data = list(imap(list, izip(*[imap(str.strip, fin)]*3)))
pprint.pprint(data)
[['party', 'sleep', 'study'],
['party', 'sleep', 'sleep'],
['study', 'sleep', 'party']]
_Steps of Execution_
1. Create a Context Manager with the file object.
2. Strip each line. (Remove newline)
3. Using zip on the iterator list of size 3, ensures that the items are grouped as tuples of three items
4. Convert tuples to list
5. Convert the generator expression to a list.
Considering all are generator expressions, its done on a single iteration.
**Instead, if your data is separated and grouped by a delimiter`------` you
can use the `itertools.groupby` solution**
from itertools import imap, groupby
class Key(object):
def __init__(self, sep):
self.sep = sep
self.count = 0
def __call__(self, line):
if line == self.sep: self.count += 1
return self.count
with open("test.txt") as fin:
data = [[e for e in v if "----------" not in e]
for k, v in groupby(imap(str.strip, fin), key = Key("----------"))]
pprint.pprint(data)
[['party', 'sleep', 'study'],
['party', 'sleep', 'sleep'],
['study', 'sleep', 'party']]
_Steps of Execution_
1. Create a Key Class, to increase a counter when ever the separator is encountered. The function call spits out the counter every-time its called apart from conditionally increasing it.
2. Create a Context Manager with the file object.
3. Strip each line. (Remove newline)
4. Group the data using `itertools.groupby` and using your custom key
5. Remove the separator from the grouped data and create a list of the groups.
|
Does the interpreter compile python scripts?
Question: I wrote a script, say, `samplescript.py`. All I can recall doing with, other
than editing it, is running it through the command-line python interpreter.
Later, I found a `samplescript.pyc` file. Does running a script through the
interpreter always invoke the compilation of the script?
Answer: When you execute your code, python creates a compiled pyc file. This file is
the one executed in posterior runs if you do not modify your code
From [here](http://docs.python.org/release/1.5.1p1/tut/node43.html):
> As an important speed-up of the start-up time for short programs that use a
> lot of standard modules, if a file called "spam.pyc" exists in the directory
> where "spam.py" is found, this is assumed to contain an already-``byte-
> compiled'' version of the module spam. The modification time of the version
> of "spam.py" used to create "spam.pyc" is recorded in "spam.pyc", and the
> file is ignored if these don't match.
>
> Normally, you don't need to do anything to create the "spam.pyc" file.
> Whenever "spam.py" is successfully compiled, an attempt is made to write the
> compiled version to "spam.pyc". It is not an error if this attempt fails; if
> for any reason the file is not written completely, the resulting "spam.pyc"
> file will be recognized as invalid and thus ignored later. The contents of
> the "spam.pyc" file is platform independent, so a Python module directory
> can be shared by machines of different architectures.
|
Python mock.patch doesn't patch the correct import
Question: # Code
def test_get_network_info(self):
with open(dirname(abspath(__file__)) + '/files/fake_network_info.txt', 'r') as mock_network_info:
with patch('subprocess.check_output', Mock(return_value=mock_network_info.read())):
self.assertEqual('192.168.1.100', get_network_info()[0])
self.assertEqual('255.255.255.0', get_network_info()[1])
self.assertEqual('192.168.1.0', get_network_info()[2])
# Error
======================================================================
ERROR: test_get_network_info (tests.test_tools.ToolsTest)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/tim/Documents/overseer/app/tests/test_tools.py", line 21, in test_get_network_info
with patch('subprocess.check_output', Mock(return_value=mock_network_info.read())):
File "/usr/local/lib/python2.7/dist-packages/mock.py", line 1268, in __enter__
original, local = self.get_original()
File "/usr/local/lib/python2.7/dist-packages/mock.py", line 1242, in get_original
"%s does not have the attribute %r" % (target, name)
AttributeError: <module 'subprocess' from '/usr/local/lib/python2.7/dist-packages/twill/other_packages/subprocess.pyc'> does not have the attribute 'check_output'
# What I understand
My understanding of the problem is that `mock` is trying to mock
[twill](https://github.com/ctb/twill)'s `subprocess` module instead of the
python one.
# Questions
1. Am I doing something wrong ?
2. How can I specify that I want to patch the python `subprocess` module and not the twill's one ? (that may have been imported earlier in the test suite)**
3. Is there another way to patch the `subprocess` module ?
# What I tried
* I tried `with patch('tools.subprocess.check_output', ...`
Doesn't work.
* I tired to use a decorator ...
Doesn't work either
* I tired to patch directly the `subprocess` module `subprocess.check_output = Mock( ...`
Works but it's not good since it doesn't undo the patching.
# Some more informations
If I run just this test and no other tests, it works because twill's
subprocess module never got imported. But as soon as I run a test using twill,
the above test will fail.
[Here](https://github.com/ctb/twill/blob/master/twill/other_packages/subprocess.py)
is the twill's version of subprocess wich looks like it has been copy pasted
from an old version of python. It doesn't have any `check_output` function and
that's why the test fails.
Twill's package comes from the [Flask-Testing](https://github.com/jarus/flask-
testing/) plugin which I use extensively. I submitted an issue on github
[here](https://github.com/jarus/flask-testing/issues/36).
I hope someone from the **lovely python community** can help. :)
Answer: See my comment up there, due to bad practices in twill, the proper way would
be to either fix twill, which may take some work, or move away to something
else, but since you now heavily depend on Flask-Testing, it's not a cheap move
either.
So this leaves us with a dirty trick: make sure to `import subprocess`
anywhere before twill is imported. Internally, this will add a reference to
the right `subprocess` module in `sys.modules`. Once a module is loaded, all
subsequents `import` won't look anymore in `sys.path` but just use the
reference already cached in `sys.modules`.
Unfortunately this is maybe not the end of the problem. Apparently twill uses
a patched version of subprocess for some reason ; and those patches won't be
available for him, since the plain built-in subprocess will be loaded instead.
It's very likely it'll crash or behave in an unexpected way. If it's the case,
well ... back to the suggestions above.
|
How to use socket with a Python client and a C++ server
Question: I have a simple client/server program.
The client is written in python as this :
import socket
import sys
HOST, PORT = "localhost", 50007
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
for x in range(0, 10000):
print("Step 1")
s.send(b'Hello')
print("Step 2")
print(str(s.recv(1000)))
print(x)
And I wrote a server in python like this :
import socket
HOST = ''
PORT = 50007
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(1)
conn, addr = s.accept()
while True:
data = conn.recv(1024)
conn.sendall(data)
I want to create a C++ version of the server. I did this :
#include <iostream>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <unistd.h>
#include <string>
#include <arpa/inet.h>
#include <string.h>
#include <stdio.h>
using namespace std;
#define SERVER_PORT htons(50007)
int main() {
char buffer[1000];
int n;
int serverSock=socket(AF_INET, SOCK_STREAM, 0);
sockaddr_in serverAddr;
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = SERVER_PORT;
serverAddr.sin_addr.s_addr = INADDR_ANY;
/* bind (this socket, local address, address length)
bind server socket (serverSock) to server address (serverAddr).
Necessary so that server can use a specific port */
bind(serverSock, (struct sockaddr*)&serverAddr, sizeof(struct sockaddr));
// wait for a client
/* listen (this socket, request queue length) */
listen(serverSock,1);
while (1 == 1) {
bzero(buffer, 1000);
sockaddr_in clientAddr;
socklen_t sin_size=sizeof(struct sockaddr_in);
int clientSock=accept(serverSock,(struct sockaddr*)&clientAddr, &sin_size);
//receive a message from a client
n = read(clientSock, buffer, 500);
cout << "Confirmation code " << n << endl;
cout << "Server received: " << buffer << endl;
strcpy(buffer, "test");
n = write(clientSock, buffer, strlen(buffer));
cout << "Confirmation code " << n << endl;
}
return 0;
}
It works one time but it block at the line `str(s.recv(1000))` of the client.
This is the output from the client :
Step 1
Step 2
b'test'
0
Step 1
Step 2
And this is the output from the server :
code 5
Server received: Hello
code 4
code 5
Server received: Hello
code 4
As you can see, the communication is like this :
1. The client send a message
2. The server receive the message
3. The server send a message
4. The client send another message
5. The server receive a message and seems to send another message but the client did not receive it.
What is my error?
Answer: In C++ server, you `accept` connection, `read`, `write`, then _leak the open
socket_ and go to wait for next client to connect.
Move your `accept` out of the loop, or add inner loop after accept.
And `close` the socket when you're done with it, before the variable with
socket number goes out of scope.
|
Project/Multiple Class Verbose Mode Python
Question: I'm wondering what the simplest way to enable debugging/verbose mode outputs
in a project that involves multiple classes/files. The answer given here:
[Easier way to enable verbose
logging](http://stackoverflow.com/questions/14097061/easier-way-to-enable-
verbose-logging) works well in a single script but what might be the best
implementation across multiple classes?
I've thought to use the Singleton design pattern to set a single instance of a
`"Debugger"` which will have a `Debugger.log("message")`. Is there a better
way to accomplish this?
Answer: This already exists. this is `logging.root` which is a `logging.Logger`
instance. You just need to set it up before using it. A simple example:
>>> import logging
>>>
>>> logging.root.setLevel('INFO')
>>> logging.root.info('Info message')
INFO:root:Info message
The logging functions for the root logger are also available from the
`logging` module directly:
>>> logging.info('Info message')
INFO:root:Info message
For a full reference on how to setup a logger see [the official python
documentation](http://docs.python.org/3.3/library/logging.html).
|
Python modules run function from file
Question: I have a python (2) project with this structure:
alerter
│ README.txt
│ __init__.py
│ __init__.pyc
│
└───lib
Alarm.py
Alarm.pyc
__init__.py
__init__.pyc
in `lib.__init__.py` I have a function that I want to call from
`lib.Alarm.py`. If I just call it in `Alarm.py` I get this error:
NameError: global name 'openDatabase' is not defined
Now I tried almost all imports at the top of the `lib.Alarm.py` file:
* `from lib import openDatabase`
ERROR: ImportError: No module named lib
* `from alerter.lib import openDatabase`
ERROR: ImportError: cannot import name openDatabase
Anyone an idea what I might try?
Answer: Try this:
from alerter import lib
lib.openDatabase()
(You don't state your Python version, which could be relevant.)
|
Generate output files from template file and csv data in python
Question: I need to generate xml files poulated with data from a csv file in python
I have two input files:
one CSV file named data.csv containing data like this:
ID YEAR PASS LOGIN HEX_LOGIN
14Z 2013 (3e?k<.P@H}l hex0914Z F303935303031345A
14Z 2014 EAeW+ZM..--r hex0914Z F303935303031345A
.......
One Template file named template.xml
<?xml version="1.0"?>
<SecurityProfile xmlns="security_profile_v1">
<year></year>
<security>
<ID></ID>
<login></login>
<hex_login></hex_login>
<pass></pass>
</security>
</SecurityProfile>
I want to get as many output files as lines in the csv data file, each output
filed named YEAR_ID, with the data from the csv file in the xml fields:
Output files contentes:
Content of output file #1 named 2013_0950014z:
<?xml version="1.0"?>
<SecurityProfile xmlns="security_profile_v1">
<year>2013</year>
<security>
<ID>14Z</ID>
<login>hex0914</login>
<hex_login>F303935303031345A</hex_login>
<pass>(3e?k<.P@H}l</pass>
</security>
</SecurityProfile>
Content of output file #2 named 2014_0950014z:
<?xml version="1.0"?>
<SecurityProfile xmlns="security_profile_v1">
<year>2014</year>
<security>
<ID>14Z</ID>
<login>hex0914</login>
<hex_login>F303935303031345A</hex_login>
<pass>EAeW+ZM..--r</pass>
</security>
</SecurityProfile>
Thank you for your suggestions.
Answer: Can you make changes the template? If so, I would do the following to make
this a bit simpler:
<?xml version="1.0"?>
<SecurityProfile xmlns="security_profile_v1">
<year>{year}</year>
<security>
<ID>{id}</ID>
<login>{login}</login>
<hex_login>{hex_login}</hex_login>
<pass>{pass}</pass>
</security>
</SecurityProfile>
Then, something like this would work:
import csv
input_file_name = "some_file.csv" #name/path of your csv file
template_file_name = "some_file.xml" #name/path of your xml template
output_file_name = "{}_09500{}.xml"
with open(template_file_name,"rb") as template_file:
template = template_file.read()
with open(filename,"rb") as csv_file:
my_reader = csv.DictReader(csv_file)
for row in my_reader:
with open(output_file_name.format(row["YEAR"],row["ID"]),"wb") as current_out:
current.write(template.format(year=row["YEAR"],
id=row["ID"],
login=row["LOGIN"],
hex_login=row["HEX_LOGIN"],
pass=row["PASS"]))
If you can't modify the template, or want to process it as XML instead of
basic string manipulation, then it's a bit more involved.
**EDIT:**
Modified answer to use csv.DictReader rather than csv.reader.
|
python opencv error finding contours
Question:  I'm trying to find the contour of the
attached image of a tshirt. FindContours returns a rectangular frame around
the tshirt, and doesn't find any additional contours. My goal is to find the
external contour of the tshirt. Any idea what am I doing wrong?
Code below. Thanks. Li
from PIL import Image
import os
import numpy
import bs4
import scipy
import cv2
STANDARD_SIZE = (200, 200)
# read image file
image_obj_orig = cv2.imread(image_file)
image_name = os.path.split(image_file)[-1]
name, extension = os.path.splitext(image_name)
# normalize to a standard size
image_obj = cv2.resize(image_obj_orig, STANDARD_SIZE)
# convert to grey-scale
greyscale_image = cv2.cvtColor(image_obj,cv2.COLOR_BGR2GRAY)
cv2.imwrite(os.path.join(trg_dir, name + '_GS' + extension), greyscale_image)
h, w = greyscale_image.shape[:2]
contours, hierarchy = cv2.findContours( greyscale_image.copy(), cv2.RETR_TREE , cv2.CHAIN_APPROX_SIMPLE)
cv2.drawContours( greyscale_image, contours, -1, (128,255,255))
cv2.imshow('image', greyscale_image)
Answer: Have you tried this:
ret,thresh = cv2.threshold(greyscale_image.copy(),127,255,cv2.THRESH_BINARY_INV) # add this line before findContours
contours, hierarchy = cv2.findContours( thresh, cv2.RETR_TREE , cv2.CHAIN_APPROX_SIMPLE)
|
cx_freeze & bundling files
Question: At present I am using pyinstaller for bundling my python application. I am
equally migrating to pyGObject (due to pygtk being depreciated).
Now pyinstaller does not support pyGObject and I have as of yet not figured
out the required hooks... One of the other downsides of pyinstaller is how it
bundles into a single executable - it causes the company installed virus
scanner to check quite intensively every time the exe is run ==> quite slow
startup.
Looking into using cx_freeze due to the pyGObject & py3 support I note it does
not have a single-executable option. That in itself isn't an issue if the
working directory can be cleaned up, be it via the pyd/dll being bundled into
a second zip or into a subdirectory.
Searching around (stackoverflow and other sites), it is illuded to that it can
be done, but I am not getting the expected results. Any idea#s?
setup.py is based around this one: <http://wiki.wxpython.org/cx_freeze>
Answer: ok solved:
1) setup.py
import sys
from cx_Freeze import setup, Executable
EXE1 = Executable(
# what to build
script = "foo.py",
initScript = None,
base = 'Win32GUI',
targetDir = "dist",
targetName = "foo.exe",
compress = True,
copyDependentFiles = True,
appendScriptToExe = True,
appendScriptToLibrary = False,
icon = 'foo.ico'
)
setup(
version = "9999",
description = "...",
author = "...",
name = "...",
options = {"build_exe": {"includes": includes,
"excludes": excludes,
"packages": packages,
"path": sys.path,
"append_script_to_exe":False,
"build_exe":"dist/bin",
"compressed":True,
"copy_dependent_files":True,
"create_shared_zip":True,
"include_in_shared_zip":True,
"optimize":2,
}
},
executables = [EXE1]
)
2) foo.py header:
import os
import sys
if getattr(sys,'frozen',False):
# if trap for frozen script wrapping
sys.path.append(os.path.join(os.path.dirname(sys.executable),'bin'))
sys.path.append(os.path.join(os.path.dirname(sys.executable),'bin\\library.zip'))
os.environ['TCL_LIBRARY'] = os.path.join(os.path.dirname(sys.executable),'bin\\tcl')
os.environ['TK_LIBRARY'] = os.path.join(os.path.dirname(sys.executable),'bin\\tk')
os.environ['MATPLOTLIBDATA'] = os.path.join(os.path.dirname(sys.executable),'bin\\mpl-data')
|
Grid search function in Python
Question: I am trying to write a parameter search function to loop over one of the
parameters and repeatedly call a function with all other parameters the same,
other than the one I am searching over. Here is some sample code:
def worker1(a, b, c):
return a + b + c
def worker2(d, e, f):
return d * e * f
def search(model, params):
res = []
# Loop over one of the parameters and repeatedly append to res
if model == 1:
res.append(worker1(**params))
elif model == 2:
res.append(worker2(**params))
return res
params = dict(a=1, b=2, c=3)
print search(1, params)
I have two workers and they are called depending on the value of the `model`
flag I pass to `search()`. The problem I am trying to solve here is to write a
loop (commented in the code) over the if statements to repeatedly call say
`worker1` by varying only one of the parameters. I want my code to be flexible
- sometimes I want to loop through `a` and keep `b` and `c` the same, but
sometimes I want to loop through `b` and keeping `a` and `c` the same.
I'm open whatever solution suggested, but I think I would be specifying the
search parameters in the `params` dictionary. E.g. To loop `a` over 1,2,3,4, I
would say:
`params = dict(a=[1,2,3,4], b=2, c=3)`
Also it would be nice if I don't have to modify the code for `worker1` and
`worker2`.
Thank you!
Answer: You could perhaps use `itertools.product` to call your workers with all
combinations of params:
<http://docs.python.org/2/library/itertools.html#itertools.product>
eg
from itertools import product
def worker1(a, b, c):
return a + b + c
def worker2(d, e, f):
return d * e * f
def search(model, *params):
res = []
# Loop over one of the parameters and repeatedly append to res
for current_params in product(*params):
if model == 1:
res.append(worker1(*current_params))
elif model == 2:
res.append(worker2(*current_params))
return res
print search(1, [1,2,3,4], [2], [3])
# more complicated combinations are possible:
print search(1, [1,2,3,4], [2,7,9], [3,13,23,43])
I've avoided using keyword arguments as your worker functions take
differently-named args so it wouldn't make much sense.
I'm assuming your worker functions don't actually look like the ones above as
if they did you could further simplify the code using the builtin `sum` and
`reduce` functions.
|
Can a spawned process communicate with the "main" MPI communicator
Question: Is there a way using MPI to let spawned processes communicate with all other
actors in the MPI_WORLD and not only with the parent that spawned the process?
Now I have two main agents, the so-called master and slave that run the
following code (spawn.py):
# Spawn test: master and first slave
import sys
from mpi4py import MPI
comm = MPI.COMM_WORLD
rank = comm.Get_rank()
if rank == 0 : # master code
print "i am the master on rank %i" % (rank)
running = True
while running :
msg = comm.recv(source=MPI.ANY_SOURCE,tag=0)
print "master received message: ", msg
if msg == "Done" :
running = False
print "master is done"
if rank == 1 : # slave code
no_spawn = 1
print "I am a slave on rank %i, about the spawn lower slaves" % (rank)
icomm = MPI.COMM_SELF.Spawn(sys.executable,args=["Cpi.py","ben"],maxprocs=no_spawn)
comm.send("Test_comm",dest=0,tag=0)
icomm.send("Test_icomm",dest=0,tag=0)
isize = icomm.Get_size()
print "on slave, isize= %i" % (isize)
rec = 0
while rec <= (no_spawn-1) :
msg = icomm.recv(source=MPI.ANY_SOURCE,tag=20)
print "slave received message: %s (rec=%i)" % (msg, rec)
rec = rec +1
import time
print "slave going to sleep\n"
time.sleep(1)
for i in range(no_spawn) :
message = ("To spawn from slave",)
icomm.send(message,dest=i,tag=0)
for i in range(no_spawn) :
message = ("Done",)
icomm.send(message,dest=i,tag=0)
msg = comm.recv(source=MPI.ANY_SOURCE,tag=0)
print "slave received message: ", msg
comm.send("Done",dest=0,tag=0)
MPI.Finalize()
The slave, in turn, spawns 1 more processes that runs the following code
(CPi.py, named after the mpi4py tutorial file):
#!/usr/bin/env python
import sys
from mpi4py import MPI
comm = MPI.COMM_WORLD
icomm = MPI.Comm.Get_parent()
irank = icomm.Get_rank()
print "Spawn irank=%i" % (irank)
message = "From_Spawn_%i"%(irank)
icomm.send(message,dest=0,tag=20)
running = True
while running :
msg = icomm.recv(source=MPI.ANY_SOURCE,tag=0)
print "Spawn on irank %i received message: %s " %(irank,msg)
if msg[0] == "Done" :
running = False
print "spawn %i sending a last msg to the master and the slave" % (irank)
comm.send(("To master from spawn",), dest=0,tag=0)
comm.send(("To slave from spawn",), dest=0,tag=0)
Between the master and slave I can send messages by using the `comm`
communicator. Between the slave and the spawned process I can send messages
over the `icomm` communicator. But what I really want is to spawn a process
and that this process can communicate with both the master and slave over the
`comm` communicator; see the last two lines of the spawned process. Is that
possible? And would it be possible for the spawned process to listen as well
to the main `comm` used by the slave and the master? Which rank would it be
send to / listen to?
The provided code does not terminate because the last two messages send by the
spawned process are neither received by the slave or the master. (I run the
code with `mpiexec -n 2 python spawn.py`)
Answer: For the process spawned by the slave to talk to the master, it would need to
create another new communicator using something like MPI_CONNECT and
MPI_ACCEPT. It's possible to do, but you'd have to use the slave to transfer
the connection details between the two.
Before you go through all of that, be sure that you can't just start your job
with more process and arbitrarily assign different roles to different ranks.
It's a pain to use intercommunicators under the best of circumstances and it's
probably simpler to start out with the correct number of processes.
|
Replacing a leading text string with the same string in python
Question: I have the following tags in a xml file as
> &\hbox{(1b)}}$$ with the initial condition <2inline-formula>$x(0)$, where
> the subscript <3inline-formula>$p$ means 'plant'; <4inline-formula>$x_{p}(t)
> \in \Re^{n}$ is the state, <5inline-formula>$y_{p}(t)\in\Re^{q}$ is the
> output, and <6inline-formula>$u_{p}(t)\in\Re^{m}$ is the input; <7inline-
> formula>
I want to replace the inline-formulas which are all starting with numbers to
`<inline-formula>` but i am not able to give the condition to search for the
inline formula staring with numbers so any help on this.. Thanks in advance
Answer: You have to use regular expresions (`re` module) for detecting one or more
digits preceeding "inline-formula" (`\d+inline-formula`).
Like this for example:
>>> import re
>>> original = "&\hbox{(1b)}}$$ with the initial condition <2inline-formula>$x(0)$, where the subscript <3inline-formula>$p$ means 'plant’; <4inline-formula>$x_{p}(t) \in \Re^{n}$ is the state, <5inline-formula>$y_{p}(t)\in\Re^{q}$ is the output, and <6inline-formula>$u_{p}(t)\in\Re^{m}$ is the input; <7inline-formula>"
>>> new = re.sub(r"<\d+inline-formula>", "<inline-formula>", original)
>>> print new
"&\\hbox{(1b)}}$$ with the initial condition <inline-formula>$x(0)$, where the subscript <inline-formula>$p$ means 'plant\xe2\x80\x99; <inline-formula>$x_{p}(t) \\in \\Re^{n}$ is the state, <inline-formula>$y_{p}(t)\\in\\Re^{q}$ is the output, and <inline-formula>$u_{p}(t)\\in\\Re^{m}$ is the input; <inline-formula>"
>>>
|
python Weather API location id
Question:
a=pywapi.get_loc_id_from_weather_com("pune")
{0: (u'TTXX0257', u'Pune, OE, Timor-leste'),
1: (u'INXX0102', u'Pune, MH, India'),
2: (u'BRPA0444', u'Pune, PA, Brazil'),
3: (u'FRBR2203', u'Punel, 29, France'),
4: (u'IDVV9705', u'Punen, JT, Indonesia'),
5: (u'IRGA2787', u'Punel, 19, Iran'),
6: (u'IRGA2788', u'Punes, 19, Iran'),
7: (u'IDYY7030', u'Punen, JI, Indonesia'),
8: (u'RSUD1221', u'Punem, UD, Russia'),
9: (u'BUXX2256', u'Punevo, 09, Bulgaria'),
'count': 10}
For the above command, I'm getting 10 results. I want a specific location like
Pune,MH,India. How do I get it?
Answer: I look the source code of pywapi, and found that the searchstring would be
quoted(url encode, e.g. ',' will be quoted to "%2C") in
`get_loc_id_from_waather_com`.
So when you call `pywapi.get_loc_id_from_weather_com(" Pune,MH,India")` it
will request the
url:`http://xml.weather.com/search/search?where=Pune%2CMH%2CIndia` but not
`http://wxdata.weather.com/wxdata/search/search?where=Pune,MH,India`. And the
formmer is certain no results.
A solution is that you can modify(hack) the pywapi. Just edit the pywapi.py
and find the `get_loc_id_from_weather_com` function. replace the line `url =
LOCID_SEARCH_URL % quote(search_string)` to `url = LOCID_SEARCH_URL %
quote(search_string, ',')` And now you can:
In [2]: import pywapi
In [3]: pywapi.get_loc_id_from_weather_com("Pune,MH,India") # no spaces
Out[3]: {0: (u'INXX0102', u'Pune, MH, India'), 'count': 1}
PS: The source code of pywapi:
def get_loc_id_from_weather_com(search_string):
"""Get location IDs for place names matching a specified string.
Same as get_location_ids() but different return format.
Parameters:
search_string: Plaintext string to match to available place names.
For example, a search for 'Los Angeles' will return matches for the
city of that name in California, Chile, Cuba, Nicaragua, etc as well
as 'East Los Angeles, CA', 'Lake Los Angeles, CA', etc.
Returns:
loc_id_data: A dictionary of tuples in the following format:
{'count': 2, 0: (LOCID1, Placename1), 1: (LOCID2, Placename2)}
"""
# Weather.com stores place names as ascii-only, so convert if possible
try:
# search_string = unidecode(search_string.encode('utf-8'))
search_string = unidecode(search_string)
except NameError:
pass
url = LOCID_SEARCH_URL % quote(search_string)
# change to:url = LOCID_SEARCH_URL % quote(search_string, ',')
try:
handler = urlopen(url)
except URLError:
return {'error': 'Could not connect to server'}
if sys.version > '3':
# Python 3
content_type = dict(handler.getheaders())['Content-Type']
else:
# Python 2
content_type = handler.info().dict['content-type']
try:
charset = re.search('charset\=(.*)', content_type).group(1)
except AttributeError:
charset = 'utf-8'
if charset.lower() != 'utf-8':
xml_response = handler.read().decode(charset).encode('utf-8')
else:
xml_response = handler.read()
dom = minidom.parseString(xml_response)
handler.close()
loc_id_data = {}
try:
num_locs = 0
for loc in dom.getElementsByTagName('search')[0].getElementsByTagName('loc'):
loc_id = loc.getAttribute('id') # loc id
place_name = loc.firstChild.data # place name
loc_id_data[num_locs] = (loc_id, place_name)
num_locs += 1
loc_id_data['count'] = num_locs
except IndexError:
error_data = {'error': 'No matching Location IDs found'}
return error_data
finally:
dom.unlink()
return loc_id_data
|
Python permutations
Question: I am trying to generate pandigital numbers using the itertools.permutations
function, but whenever I do it generates them as a list of separate digits,
which is not what I want.
For example:
for x in itertools.permutations("1234"):
print(x)
will produce:
('1', '2', '3', '4')
('1', '2', '4', '3')
('1', '3', '2', '4')
('1', '3', '4', '2')
('1', '4', '2', '3')
('1', '4', '3', '2'), etc.
whereas I want it to return 1234, 1243, 1324, 1342, 1423, 1432, etc. How would
I go about doing this in an optimal fashion?
Answer: A list comprehension with the built-in `str.join()` function is what you need:
import itertools
a = [''.join(i) for i in itertools.permutations("1234") ]
print(a)
Output:
['1234', '1243', '1324', '1342', '1423', '1432', '2134', '2143', '2314', '2341', '2413', '2431', '3124', '3142', '3214', '3241', '3412', '3421', '4123', '4132', '4213', '4231', '4312', '4321']
|
How to get a percentile for an empirical data distribution and get it's x-coordinate?
Question: I have some discrete data values, that taken together form some sort of
distribution. This is one of them, but they are different with the peak being
in all possible locations, from 0 to end. 
So, I want to use it's quantiles (percentiles) in Python. I think I could
write some sort of function, that would some up all values starting from zero,
until it reaches desired percent. But probably there is a better solution? For
example, to create an empirical distribution of some sort in SciPy and then
use SciPy's methods of calculating percentiles?
In the very end I need x-coordinates of a left percentile and a right
percentile. One could use 20% and 80% percentiles as an example, I will have
to find the best numbers for my case later.
Thank you in advance!
**EDIT:** some example code for almost what I want.
import numpy as np
np.random.seed(0)
distribution = np.random.normal(0, 1, 1000)
left, right = np.percentile(distribution, [20, 80])
print left, right
This returns percentiles themselves, I need to get their x-coordinates
somehow. For normal distribution here it is possible, obviously, but I have a
distribution of an unknown shape, so if a percentile isn't equal to one of the
values (which is the most common thing, obviously), it becomes much more
complicated.
Answer: if you are looking for empirical CDF then you may use statsmodels
[ECDF](http://statsmodels.sourceforge.net/devel/generated/statsmodels.tools.tools.ECDF.html).
For percentiles/quantiles you can use numpy
[percentile](http://docs.scipy.org/doc/numpy/reference/generated/numpy.percentile.html)
|
How to log both to console and file using Python?
Question: I am working Python and I need to logger so I decided to start using
RotatingFileHandler. Below is my `logging.conf` file
[loggers]
keys=root
[handlers]
keys=logfile
[formatters]
keys=logfileformatter
[logger_root]
level=DEBUG
handlers=logfile
[formatter_logfileformatter]
format=%(asctime)s %(name)-12s: %(levelname)s %(message)s
[handler_logfile]
class=handlers.RotatingFileHandler
level=NOTSET
args=('ookagent.log', 'a', 50000000000, 5)
formatter=logfileformatter
And below is my Python script from which I am successfully able to log to the
files. But I am not sure how to log both to files and console as well.
#!/usr/bin/python
import logging
import logging.config
import logging.handlers
# using RotatingFileHandler for logging purpose
logging.config.fileConfig('logging.conf')
ooklogger = logging.getLogger('')
ooklogger.info("HelloWorld")
Can we make a change in my logging.conf file by which I can login both to
console and files as well? Is it possible to do that?
Answer: Sure, the logging configuration file format lets you specify multiple
handlers. You can use a `StreamHandler` to log to the console. That would
entail modifications like these to your config file:
[handlers]
keys=logfile,logconsole
[handler_logconsole]
class=StreamHandler
# other configuration directives as you like
[logger_root]
handlers=logfile,logconsole
See the [config file
documentation](http://docs.python.org/2/library/logging.config.html#configuration-
file-format) for more information and examples.
|
Dialogs tripping up in Vala
Question: I've been experimenting with Vala programming recently. I've got pretty
extensive experience programming in other languages, but in recent years have
stuck mainly with scripting languages like Python, Tcl and Perl. I was
impressed by the clean look of Elementary OS, which is what started me looking
into Vala, and I must say that my first impressions are very positive.
However, I have hit a snag with Dialog programming, which I thought more
experienced Vala programmers might be able to help with. In my latest test
program I use a Dialog-based routine to obtain a value (getYesNo), and then
display a string describing that value to screen using another Dialog-based
routine (showDialog). Both routines work correctly when used independently,
but when used together as described the display event is held back until a
second call is made to the value-obtaining routine. This sounds like the sort
of situation that a call to "flush_events" would solve in Perl or Tcl. But how
can I deal with it in Vala? Or is there a way to avoid it happening in the
first place?
Code:
using Gtk;
using Posix;
public class DialogTestWindow: ApplicationWindow {
private int RESPONSE;
private Toolbar tbMain = new Toolbar();
private ToolButton bAbout = new ToolButton(new Image.from_icon_name
("help-about",IconSize.SMALL_TOOLBAR),null);
private ToolButton bDoIt = new ToolButton(new Image.from_icon_name
("media-record",IconSize.SMALL_TOOLBAR),null);
private ToolButton bQuit = new ToolButton(new Image.from_icon_name
("application-exit",IconSize.SMALL_TOOLBAR),null);
internal DialogTestWindow(DialogTest app) {
Object(application: app, title: "DialogTest");
this.window_position = WindowPosition.CENTER;
this.set_default_size(720,480);
// ---- Set up Toolbar ----------------------------------------------------
tbMain.get_style_context().add_class(STYLE_CLASS_PRIMARY_TOOLBAR);
bQuit.is_important = true;
bQuit.clicked.connect(onQuit);
tbMain.add(bQuit);
bAbout.is_important = true;
bAbout.clicked.connect(onAbout);
tbMain.add(bAbout);
bDoIt.is_important = true;
bDoIt.clicked.connect(onDoIt);
tbMain.add(bDoIt);
// ---- Pack Toolbar etc into vBox on main window -------------------------
Box vbMain = new Box(Orientation.VERTICAL,0);
vbMain.pack_start(tbMain,false,true,0);
this.add(vbMain);
this.show_all();
printf("Started\n");
}
// ==== getYesNo ==========================================================
private void getYesNo(string message) {
Dialog dialog = new Dialog.with_buttons
("Get",this,DialogFlags.MODAL,
Stock.YES,ResponseType.YES,Stock.NO,ResponseType.NO,null);
var content = dialog.get_content_area();
// warning: assignment from incompatible pointer type
// [enabled by default]
Label label = new Label(message);
label.set_line_wrap(true);
content.add(label);
dialog.response.connect((id)=>{
printf("response id=%i\n",id);
RESPONSE = id;
dialog.destroy();
});
dialog.show_all();
}
// ==== onAbout ===========================================================
private void onAbout() {
Dialog dialog = new Dialog.with_buttons
("About",this,DialogFlags.MODAL,
Stock.OK,ResponseType.OK,null);
var content = dialog.get_content_area();
// warning: assignment from incompatible pointer type
// [enabled by default]
Label label = new Label("This program tests pop-up dialogs");
content.add(label);
dialog.response.connect(()=>{dialog.destroy();});
dialog.show_all();
}
// ==== onDoIt ============================================================
private void onDoIt() {
getYesNo("Well?");
if (RESPONSE==ResponseType.YES) showDialog("YES!");
}
// ==== onQuit ============================================================
private void onQuit() {
printf("Ending\n");
exit(-1);
}
// ==== showDialog ========================================================
private void showDialog(string message) {
Dialog dialog = new Dialog.with_buttons
("Show",this,DialogFlags.MODAL,
Stock.OK,ResponseType.OK,null);
var content = dialog.get_content_area();
// warning: assignment from incompatible pointer type
// [enabled by default]
Label label = new Label(message);
label.set_line_wrap(true);
content.add(label);
dialog.response.connect((id)=>{dialog.destroy();});
dialog.show_all();
}
}
public class DialogTest: Gtk.Application {
internal DialogTest() {
Object(application_id: "org.test.DialogTest");
}
protected override void activate() {
new DialogTestWindow(this).show();
}
}
extern void exit(int exit_code);
public int main(string[] args) {
return new DialogTest().run(args);
}
Answer: Use Gtk.Dialog.run, not Gtk.Widget.show_all. That will block the main loop
until the dialog returns a result instead of displaying the two dialogs
simultaneously.
|
fitting multivariate curve_fit in python
Question: I'm trying to fit a simple function to two arrays of independent data in
python. I understand that I need to bunch the data for my independent
variables into one array, but something still seems to be wrong with the way
I'm passing variables when I try to do the fit. (There are a couple previous
posts related to this one, but they haven't been much help.)
import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit
def fitFunc(x_3d, a, b, c, d):
return a + b*x_3d[0,:] + c*x_3d[1,:] + d*x_3d[0,:]*x_3d[1,:]
x_3d = np.array([[1,2,3],[4,5,6]])
p0 = [5.11, 3.9, 5.3, 2]
fitParams, fitCovariances = curve_fit(fitFunc, x_3d[:2,:], x_3d[2,:], p0)
print ' fit coefficients:\n', fitParams
The error I get reads,
raise TypeError('Improper input: N=%s must not exceed M=%s' % (n, m))
TypeError: Improper input: N=4 must not exceed M=3
What is `M` the length of? Is `N` the length of `p0`? What am I doing wrong
here?
Answer: N and M are defined in [the
help](http://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.curve_fit.html)
for the function. N is the number of data points and M is the number of
parameters. Your error therefore basically means you need at least as many
data points as you have parameters, which makes perfect sense.
This code works for me:
import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit
def fitFunc(x, a, b, c, d):
return a + b*x[0] + c*x[1] + d*x[0]*x[1]
x_3d = np.array([[1,2,3,4,6],[4,5,6,7,8]])
p0 = [5.11, 3.9, 5.3, 2]
fitParams, fitCovariances = curve_fit(fitFunc, x_3d, x_3d[1,:], p0)
print ' fit coefficients:\n', fitParams
I have included more data. I have also changed `fitFunc` to be written in a
form that scans as only being a function of a single x - the fitter will
handle calling this for all the data points. The code as you posted also
referenced `x_3d[2,:]`, which was causing an error.
|
python list memory usage
Question: I am trying to improve the memory usage of my script in python, therefore I
need to know what's RAM usage of my list. I measure the memory usage with
print str(sys.getsizeof(my_list)/1024/1024)
which hopefully would give me the size of the list in RAM in Mb.
it outputs 12 Mb, however in `top` command I see that my script uses 70% of
RAM of 4G laptop when running.
In addition this list should contain a content from file of ~500Mb.
So 12Mb is unrealistic.
How can I measure the real memory usage?
Answer: `sys.getsizeof` only take account of the list itself, not items it contains.
According to [`sys.getsizeof`
documentation](http://docs.python.org/3/library/sys.html#sys.getsizeof):
> ... Only the memory consumption directly attributed to the object is
> accounted for, not the memory consumption of objects it refers to. ...
Use [Pympler](https://pypi.python.org/pypi/Pympler/):
>>> import sys
>>> from pympler.asizeof import asizeof
>>>
>>> obj = [1, 2, (3, 4), 'text']
>>> sys.getsizeof(obj)
48
>>> asizeof(obj)
176
|
Adding elements to an JSON object in a external JSON file?
Question: * * *
(After months of surfing the internet, talking to the school's computing
department and try code out, I still don't get how to do it, but I do know
more specific about what I trying to do)
* * *
Previously I said I want to "Add lines" to a existing JSON file.
What I want to do is simply add an element to an JSON object from a file, then
save the file. However I am still confused about how to do it.
The process I am guessing is to use ajax to load the content of the file (the
JSON code in the file) into a variable then add the new element into the
object then save the file.
I have seen a lot of code but are all just too confusing and looks like its
for webpages. I am trying to edit a file on the computer as a program which I
think webpage related code such as xmlhttp requests are irrelevant as the file
is in a folder in appdata.
I have been confused and thought Java and Javascript were the same thing, I
know now they're not.
What code or functions would I look for and how would it be used in the code?
(Please don't post pseudocode because I have no idea how to write the code for
them since I have literally no idea how to code anything other than a html
webpage and some php. Other coding language like Java, Javascript and Python I
have little knowledge with but not enough to write a program alone.)
Answer: I think it would be best to use code that somebody else has already written to
manipulate the JSON. There are plenty of libraries for that, and the best
would be the officially specified one, [JSON-P](https://jsonp.java.net). What
you would do is this:
1. Go to <http://jsonp.java.net/> and download JSON-P. (You will have to examine the page carefully to find the link to "[JSON Processing RI jar](http://search.maven.org/remotecontent?filepath=org/glassfish/javax.json/1.0.4/javax.json-1.0.4.jar)".) You will need to include this JAR in your class path while you write your program.
2. Add imports to your program for `javax.json.*`.
3. Write this code to do the job (you will have to catch `JsonException`s and `IOException`s):
JsonReader reader = Json.createReader(new FileReader("launcher_profiles.json"));
JsonObject file = reader.readObject();
reader.close();
JsonObject profiles = file.getJsonObject("profiles");
JsonObject newProfile = Json.createObjectBuilder()
.add("name", "New Lines")
.add("gameDir", "New Lines")
.add("lastVersionId", "New Lines")
.add("playerUUID", "")
.build();
JsonObjectBuilder objectBuilder = Json.createObjectBuilder()
.add("New Profile Name", newProfile);
for (java.util.Map.Entry<String, JsonValue> entry : profiles.entrySet())
objectBuilder.add(entry.getKey(), entry.getValue());
JsonObject newProfiles = objectBuilder.build();
// Now, figure out what I have done so far and write the rest of the code yourself! At the end, use this code to write out the new file:
JsonWriter writer = Json.createWriter(new FileWriter("launcher_profiles.json"));
writer.writeObject(newFile);
writer.close();
|
How to import liblas module in Python?
Question: I am using liblas for python to read .las file. When I enter:
from liblas import file
It gives me:
> No module named liblas.
I already set up las library path in system, `lasinfo` is working fine. Can
anyone tell me how to import las library in Python? I am using Ubuntu by the
way.
Answer: It looks like the liblas is not properly installed or you configured the path
incorrectly. Try installing the package **liblas** using pip or easy_install.
$ easy_install liblas OR $ pip install liblas
|
iPython: 'no module named' ImportError
Question: Windows: I have the Python package CVXOPT installed on my computer for the
regular Python distribution, though not specifically with Anaconda, so it
imports fine when I'm doing text editor/cmd python scripting. I tried
installing CVXOPT with Anaconda, but that didn't work so I'm having to import
the library directly when working with iPython.
My directory structure looks like:
C:
--Python27
----Lib
------site-packages
--------cvxopt
----------__init__.py
----------.....
The error occurs when I run this code in an iPython notebook:
import sys
sys.path.append('C:\Python27\Lib\site-packages\cvxopt')
import cvxopt
The error:
ImportError: No module named cvxopt
How can I fix this? Perhaps I'm appending the path incorrectly?
Answer: You're defining a path a bit too deep in your file tree. You need to add to
`sys.path` the folder just before your module:
import sys
sys.path.append('C:\Python27\Lib\site-packages')
import cvxopt
Here, `cvxopt` can be found in the `site-packages` folder. If you add the
`cvxopt` folder in the sys path, it'll search a module of that name in the
folder itself and will not checked the base folder.
|
Python regex on wikitext template
Question: I'm trying to remove line breaks with Python from wikitext templates of the
form:
{{cite web
|title=Testing
|url=Testing
|editor=Testing
}}
The following should be obtained with re.sub:
{{cite web|title=Testing|url=Testing|editor=Testing}}
I've been trying with Python regex for hours, yet haven't succeeded at it. For
example I've tried:
while(re.search(r'\{cite web(.*?)([\r\n]+)(.*?)\}\}')):
textmodif=re.sub(r'\{cite web(.*?)([\r\n]+)(.*?)\}\}', r'{cite web\1\3}}', textmodif,re.DOTALL)
But it doesn't work as expected (even without the while loop, it's not working
for the first line break).
I found this similar question but it didnt help: [Regex for MediaWiki wikitext
templates](http://stackoverflow.com/questions/8982251/regex-for-mediawiki-
wikitext-templates) . I'm quite new at Python so please don't be too hard on
me :-)
Thank you in advance.
Answer: You need to switch on newline matching for `.`; it does _not_ match a newline
otherwise:
re.search(r'\{cite web(.*?)([\r\n]+)(.*?)\}\}', inputtext, flags=re.DOTALL)
You have multiple newlines spread throughout the text you want to match, so
matching just one set of consecutive newlines is not enough.
From the [`re.DOTALL`
documentation](http://docs.python.org/2/library/re.html#re.S):
> Make the `'.'` special character match any character at all, including a
> newline; without this flag, `'.'` will match anything _except_ a newline.
You could use one `re.sub()` call to remove all newlines within the `cite`
stanza in one go, without a loop:
re.sub(r'\{cite web.*?[\r\n]+.*?\}\}', lambda m: re.sub('\s*[\r\n]\s*', '', m.group(0)), inputtext, flags=re.DOTALL)
This uses a nested regular expression to remove all whitespace with at least
one newline in it from the matched text.
Demo:
>>> import re
>>> inputtext = '''\
... {{cite web
... |title=Testing
... |url=Testing
... |editor=Testing
... }}
... '''
>>> re.search(r'\{cite web(.*?)([\r\n]+)(.*?)\}\}', inputtext, flags=re.DOTALL)
<_sre.SRE_Match object at 0x10f335458>
>>> re.sub(r'\{cite web.*?[\r\n]+.*?\}\}', lambda m: re.sub('\s*[\r\n]\s*', '', m.group(0)), inputtext, flags=re.DOTALL)
'{{cite web|title=Testing|url=Testing|editor=Testing}}\n'
|
using html5lib with xml.etree.ElementTree
Question: I need is a way to use the html5lib parser to generate a real
xml.etree.ElementTree. (lxml is not an option for portability reasons.)
`ELementTree.parse` [can take a
parser](http://docs.python.org/2/library/xml.etree.elementtree.html#xml.etree.ElementTree.parse)
as an optional parameter
xml.etree.ElementTree.parse(source, parser=None)
but it's not clear what such a parser would look like. Is there a class or
object within HTML5 I could use for the `parser` argument? Documentation for
both libraries on this issue is thin.
* * *
**Context** :
I have a malformed XHTML file that can't be parsed with `ElementTree.parse`:
<?xml version="1.0" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Title</title></head>
<body><div class="cls">Note that this br<br>is missing a closing slash</div></body>
</html>
So I used `html5lib.parse` instead with the default `treebuilder="etree"`
parameter, which worked fine.
But html5lib apparently does not output an `xml.etree.ElementTree` object,
just one with a near-identical API. There are two problems with this:
* html5lib's `find` does not support the [`namespaces` parameter](http://stackoverflow.com/a/14853417/1180926), making XPath excessively verbose without a clumsy [wrapper function](http://stackoverflow.com/a/1704596/1180926).
* The Eclipse debugger does not support drill-through of html5lib etrees.
So I cannot use either ElementTree or html5lib alone.
Answer: Given `xml.etree.ElementTree` as `etree` (as it is commonly imported as):
What's returned is not an `etree.ElementTree`, but rather an `etree.Element`
(this is the same as what `etree.fromstring` returns; only `etree.parse`
returns an `etree.ElementTree`). It is genuinely part of the etree module —
it's not something with a similar API. The problem you've run into applies to
`etree.fromstring` as much as it does html5lib.
The Python [documentation for
`xml.etree.ElementTree`](http://docs.python.org/2/library/xml.etree.elementtree.html)
doesn't mention the `namespaces` argument — it seems to be an undocumented
feature of `ElementTree` objects (but not `Element` objects). As such, it's
probably not something that should really be relied on! Your best bet is
likely going to be to use a wrapper function.
The fact that Eclipse cannot go through the trees is down to the fact that
html5lib defaults to `xml.etree.cElementTree` when it exists — which is meant
to be identical, per the module's documentation, but is implemented in C using
CPython's API, stopping Eclipse's debugger from functioning. You can get a
treebuilder using the non-accelerated version (note from Python 3.3 _both_ are
the C implementation — `cElementTree` merely survives as a deprecated alias)
using the below:
import xml.etree.ElementTree as etree
import html5lib
tb = html5lib.getTreeBuilder("etree", implementation=etree)
p = html5lib.HTMLParser(tb)
tree = p.parse("<html>")
|
Python - directed edge list to dictionary of dictionaries
Question: I have a list of directed edges in a file in the form
Source_Id Target_Id Edge_Type
A B Train
A C Bus
B D Bus
C A Train
... ...
I would like to structure the data in a dictionary of dictionaries such as:
{'A': {'B': 'Train', 'C': 'Bus'}, 'B': {'D': 'Bus'}, 'C': {'A': 'Train'}}
What is the best way to do that?
Answer: Use a
[`collections.defaultdict()`](http://docs.python.org/2/library/collections.html#collections.defaultdict)
object to materialize the values for you:
from collections import defaultdict
import csv
graph = defaultdict(dict)
with open('inputfile', 'rb') as infh:
reader = csv.reader(infh, delimiter='\t')
next(reader, None) # skip header
for source, target, edge in reader:
graph[source][target] = edge
This assumes there is only one edge between each source and target, and that
the inputfile is tab delimited.
If there are multiple edges, build a list of edge names instead:
graph = defaultdict(lambda: defaultdict(list))
with open('inputfile', 'rb') as infh:
reader = csv.reader(infh, delimiter='\t')
next(reader, None) # skip header
for source, target, edge in reader:
graph[source][target].append(edge)
giving you
{'A': {'C': ['Bus'], 'B': ['Train']}, 'C': {'A': ['Train']}, 'B': {'D': ['Bus']}}
where the edge lists can then represent more edge names.
|
Getting URLError Exception when caching webdriver instances
Question: I am attempting to cache webdriver instances across test case classes. I do
not need a "clean" webdriver since I am simply using PhantomJS to query the
DOM (I do need JavaScript enabled, which is why I am not simply fetching the
source and parsing that).
The cache is a dictionary with the URL as a key and the driver instance as
value. The cache is in the base test case, and I call get() which is a method
on the base test case. This method instantiates webdriver, and goes to the url
if the driver is not in the cache already.
It appears there's some kind of socket issue when trying to access driver
properties on the cached instance in the second test case (derivedb.py). I'd
appreciate if someone could tell how to get this work.
I am getting the following output:
$ python launcher.py
test_a (deriveda.DerivedTestCaseA) ... Instantiate new driver
Title is: Google
ok
test_b (deriveda.DerivedTestCaseA) ... Retrieve driver from cache
Title is: Google
ok
test_a (derivedb.DerivedTestCaseB) ... Retrieve driver from cache
ERROR
======================================================================
ERROR: test_a (derivedb.DerivedTestCaseB)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/cohenaa/PycharmProjects/sanity/derivedb.py", line 7, in test_a
print "Title is: %s" % self.driver.title
File "/Users/cohenaa/sanity-env/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 185, in title
resp = self.execute(Command.GET_TITLE)
File "/Users/cohenaa/sanity-env/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 162, in execute
response = self.command_executor.execute(driver_command, params)
File "/Users/cohenaa/sanity-env/lib/python2.7/site-packages/selenium/webdriver/remote/remote_connection.py", line 349, in execute
return self._request(url, method=command_info[0], data=data)
File "/Users/cohenaa/sanity-env/lib/python2.7/site-packages/selenium/webdriver/remote/remote_connection.py", line 410, in _request
resp = opener.open(request)
File "/sw/lib/python2.7/urllib2.py", line 404, in open
response = self._open(req, data)
File "/sw/lib/python2.7/urllib2.py", line 422, in _open
'_open', req)
File "/sw/lib/python2.7/urllib2.py", line 382, in _call_chain
result = func(*args)
File "/sw/lib/python2.7/urllib2.py", line 1214, in http_open
return self.do_open(httplib.HTTPConnection, req)
File "/sw/lib/python2.7/urllib2.py", line 1184, in do_open
raise URLError(err)
URLError: <urlopen error [Errno 61] Connection refused>
----------------------------------------------------------------------
Ran 3 tests in 1.271s
FAILED (errors=1)
**launcher.py**
import unittest
from deriveda import DerivedTestCaseA
from derivedb import DerivedTestCaseB
suite = unittest.TestSuite()
testclasses = [DerivedTestCaseA, DerivedTestCaseB]
testloader = unittest.TestLoader()
classes_to_names = {}
for tc in testclasses:
classes_to_names[tc] = testloader.getTestCaseNames(tc)
for tc in classes_to_names:
for testname in classes_to_names[tc]:
suite.addTest(tc(testname))
unittest.TextTestRunner(verbosity=10).run(suite)
**deriveda.py**
from basetestcase import BaseTestCase
from unittest import main
class DerivedTestCaseA(BaseTestCase):
def test_a(self):
self.get("http://www.google.com")
print "Title is: %s" % self.driver.title
def test_b(self):
self.get("http://www.google.com")
print "Title is: %s" % self.driver.title
**derivedb.py**
from basetestcase import BaseTestCase
class DerivedTestCaseB(BaseTestCase):
def test_a(self):
self.get("http://www.google.com")
print "Title is: %s" % self.driver.title
**basetestcase.py:**
import unittest
from selenium import webdriver
class BaseTestCase(unittest.TestCase):
cache = {}
def get(self, url):
if url not in self.cache:
print "Instantiate new driver"
self.driver = webdriver.PhantomJS()
self.driver.get(url)
self.cache[url] = self.driver
else:
print "Retrieve driver from cache"
self.driver = self.cache[url]
@classmethod
def tearDownClass(cls):
for url in BaseTestCase.cache:
BaseTestCase.cache[url].quit()
Answer: Ahhh. I see now. The driver is quitting after each test case. If I quit after
the suite is run instead, no error.
|
python - specifically handle file exists exception
Question: I have come across examples in this forum where a specific error around files
and directories is handled by testing the `errno` value in `OSError` (or
`IOError` these days ?). For example, some discussion here - [Python's
"open()" throws different errors for "file not found" \- how to handle both
exceptions?](http://stackoverflow.com/questions/15032108/pythons-open-throws-
different-errors-for-file-not-found-how-to-handle-b). But, I think, that is
not the right way. After all, a `FileExistsError` exists specifically to avoid
having to worry about `errno`.
The following attempt didn't work as I get an error for the token
`FileExistsError`.
try:
os.mkdir(folderPath)
except FileExistsError:
print 'Directory not created.'
How do you check for this and similar other errors specifically ?
Answer: According to the code `print ...`, it seems like you're using Python 2.x.
[`FileExistsError`](http://docs.python.org/3/library/exceptions.html#FileExistsError)
was added in Python 3.3; You can't use `FileExistsError`.
Use
[`errno.EEXIST`](http://docs.python.org/2/library/errno.html#errno.EEXIST):
import os
import errno
try:
os.mkdir(folderPath)
except OSError as e:
if e.errno == errno.EEXIST:
print('Directory not created.')
else:
raise
|
Parse output of 'ip addr' via Python
Question: I need some help parsing the output of the `ip addr` command as dumped to a
text file, with contents like this:
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN \ link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
1: lo inet 127.0.0.1/8 scope host lo
1: lo inet6 ::1/128 scope host \ valid_lft forever preferred_lft forever
2: em1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000\ link/ether b8:ca:3a:65:43:3c brd ff:ff:ff:ff:ff:ff
3: em2: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000\ link/ether b8:ca:3a:65:43:3c brd ff:ff:ff:ff:ff:ff
4: em3: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond1 state UP qlen 1000\ link/ether b8:ca:3a:65:43:3e brd ff:ff:ff:ff:ff:ff
5: em4: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond1 state UP qlen 1000\ link/ether b8:ca:3a:65:43:3e brd ff:ff:ff:ff:ff:ff
6: p1p1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000\ link/ether a0:36:9f:27:13:48 brd ff:ff:ff:ff:ff:ff
7: p1p2: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000\ link/ether a0:36:9f:27:13:49 brd ff:ff:ff:ff:ff:ff
8: p1p3: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000\ link/ether a0:36:9f:27:13:4a brd ff:ff:ff:ff:ff:ff
9: p1p4: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000\ link/ether a0:36:9f:27:13:4b brd ff:ff:ff:ff:ff:ff
10: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP \ link/ether b8:ca:3a:65:43:3c brd ff:ff:ff:ff:ff:ff
10: bond0 inet6 fe80::baca:3aff:fe65:433c/64 scope link \ valid_lft forever preferred_lft forever
12: bond1: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP \ link/ether b8:ca:3a:65:43:3e brd ff:ff:ff:ff:ff:ff
12: bond1 inet6 fe80::baca:3aff:fe65:433e/64 scope link \ valid_lft forever preferred_lft forever
As you can see, there will be lines that start similarly (^\d: $device), and
I'm at a loss of how to be able to iterate over the file, and pull out select
information (ipv4 addr, ipv6 addr if present, link state, hw addr) for each
device when this information is spread over multiple lines.
Suggestions?
Answer:
from itertools import groupby
interfaces = {}
with open('ip.txt') as f:
lines = [line for line in f if line.strip()]
# group by line number
for key, group in groupby(lines, lambda x: x.split()[0]):
interface = []
for thing in group:
# append lines without repeating part
interface += thing.split()[2:]
if interface:
interfaces[key] = interface
for key, interface in interfaces.items():
for x in ['inet', 'inet6', 'state', 'link/ether']:
if x in interface:
idx = interface.index(x)
print '%s %s=%s' % (key, x, interface[idx+1])
$ python ip.py
3: state=UP
3: link/ether=b8:ca:3a:65:43:3c
4: state=UP
4: link/ether=b8:ca:3a:65:43:3e
5: state=UP
5: link/ether=b8:ca:3a:65:43:3e
1: inet=127.0.0.1/8
1: inet6=::1/128
1: state=UNKNOWN
10: inet6=fe80::baca:3aff:fe65:433c/64
10: state=UP
10: link/ether=b8:ca:3a:65:43:3c
2: state=UP
2: link/ether=b8:ca:3a:65:43:3c
8: state=DOWN
8: link/ether=a0:36:9f:27:13:4a
9: state=DOWN
9: link/ether=a0:36:9f:27:13:4b
12: inet6=fe80::baca:3aff:fe65:433e/64
12: state=UP
12: link/ether=b8:ca:3a:65:43:3e
6: state=DOWN
6: link/ether=a0:36:9f:27:13:48
7: state=DOWN
7: link/ether=a0:36:9f:27:13:49
|
Open a read-only Excel file using Python
Question: I have a program (zTree) that is writing an Excel file and updating it
constantly. What I need this Python program to do is read in the data from the
Excel file as its updating. The problem that I'm having though is that when I
try to read in the data using xlrd, I get the error:
peek = f.read(peeksz)
IO Error: [Errno 13] Permission denied
which comes up because Excel is in read-only mode. Is there any way to read in
the data of an Excel file in read-only mode using Python?
Answer: just tested it on win 7 (64bit), but in this case it works:
import xlrd
workbook = xlrd.open_workbook('C:/User/myaccount/Book1.xls')
worksheet = workbook.sheet_by_name('Sheet1')
print worksheet
could it be, that you are trying to copy it first, or that your python is
trying to put a temporary copy of the file in the py-directoy? - because that
would give the IO-Error
|
Python Updating RRDTool with Serial Port Data
Question: I am trying to update a RRDTool DB with serial information. Is it possible to
declare the serial data as a variable in the update line? Using the code
below, rrdtool doesn't see the N: timestamp. However if I manually enter the
data following the "N:" it will update.
import serial
import time
import numpy
import sys
import rrdtool
ser = serial.Serial('/dev/ttyUSB0', 9600)
time.sleep(1)
ser.flush()
for i in range(2):
ser.readline()
while 1:
# Read data
temp = ser.readline()
ret = rrdtool.update('temperature.rrd', 'N:', temp)
if ret:
print rrdtool.error()
time.sleep(5)
quit()
Answer: I believe you want to do something like this:
ret = rrdtool.update('temperature.rrd', 'N:%s' % temp)
Each argument in an rrdtool wrapper function should correspond to an argument
in the rrdtool cli command. So in your previous example when you were running
rrdtool.update with 3 arguments you were actually running something like:
rrdtool update temperature.rrd N: 65.6
the update should be a single argument, so this is really what you wanted:
rrdtool update temperature.rrd N:65.6
|
Mod_wsgi fails to load django.core.handlers.wsgi
Question: Ok, after 5-6 hours of trying, I give up. I have searched the web, tried all
solutions suggested, but nothing is solving my problem.
**Goal:** Set up Django on my Ubuntu 12.04 VPS.
**Problem:** `Exception occurred processing WSGI script [...] ImportError: No
module named django.core.handlers.wsgi` in /etc/log/apache2/error.log.
**Solutions tried:** 1) Appending the site-packages directory to the sys path
in Djangos' wsgi.py file, 2) re-installing mod_wsgi, 3) making sure mod_wsgi
is compiled for the same Python version as Django is installed with, 4) chmod
777 for the site-packages directory.
**Environment:** Ubuntu 12.04 VPS, Django installation in virtualenv, Python
version 2.7.3, Django version 1.6.1, mod_wsgi built from
[mod_wsgi-3.4.tar.gz](https://code.google.com/p/modwsgi/downloads/list).
**Full error message:**
mod_wsgi (pid=23691): Exception occurred processing WSGI script '/var/www/mySite/djangoSite/djangoSite/wsgi.py'.
Traceback (most recent call last):
File "/var/www/mySite/djangoSite/djangoSite/wsgi.py", line 7, in <module>
import django.core.handlers.wsgi
ImportError: No module named django.core.handlers.wsgi
mod_wsgi (pid=23691): Target WSGI script '/var/www/mySite/djangoSite/djangoSite/wsgi.py' cannot be loaded as Python module.
mod_wsgi (pid=23691): Exception occurred processing WSGI script '/var/www/mySite/djangoSite/djangoSite/wsgi.py'.
Traceback (most recent call last):
File "/var/www/mySite/djangoSite/djangoSite/wsgi.py", line 7, in <module>
import django.core.handlers.wsgi
ImportError: No module named django.core.handlers.wsgi
**Conf file from sites-available:**
<VirtualHost *:80>
ServerAdmin [email protected]
ServerName mysite.com
DocumentRoot /var/www/mysite.com/djangoSite
WSGIDaemonProcess djangoSite python-path=/var/www/mysite.com/djangoSite:~/Envs/myEnv/lib/python2.7/site-packages
WSGIProcessGroup djangoSite
WSGIScriptAlias / /var/www/mysite.com/djangoSite/djangoSite/wsgi.py
Alias /static/ /var/www/mysite.com/djangoSite/static/
<Directory /var/www/mysite.com/djangoSite/static>
Order deny,allow
Allow from all
</Directory>
<Directory /var/www/mysite.com/djangoSite/djangoSite>
<Files wsgi.py>
Order deny,allow
Allow from all
</Files>
</Directory>
</VirtualHost>
**wsgi.py:**
import os
import sys
sys.path.append('/var/www/mysite.com/djangoSite/')
sys.path.append('/var/www/mysite.com/djangoSite/djangoSite/')
activate_this = '/root/Envs/myenv/bin/activate_this.py'
execfile(activate_this, dict(__file__=activate_this))
os.environ['DJANGO_SETTINGS_MODULE'] = 'djangoSite.settings'
import django.core.handlers.wsgi
application = django.core.handlers.wsgi.WSGIHandler()
**Site structure**
/var/www/
-- mysite.com
-- djangoSite
-- manage.py
-- djangoSite
-- settings.py, wsgi.py etc.
Answer: In your wsgi.py, try adding this to activate virtual env:
import os
import sys
sys.path.append('/Path_To/Virtual_Env/Project_Dir/')
#This is important if multiple apps are running (instead of setdefault)
os.environ["DJANGO_SETTINGS_MODULE"] = "app_name.settings"
activate_this = '/Path_To/Virtual_Env/bin/activate_this.py'
execfile(activate_this, dict(__file__=activate_this))
In you apache config, you mainly need only(No Deamon Process required):
WSGIScriptAlias / /var/www/mysite.com/djangoSite/djangoSite/wsgi.py
Alias /static/ /var/www/mysite.com/djangoSite/static/
See from the **Create Virtual Host** section of [this
link](http://thecodeship.com/deployment/deploy-django-apache-virtualenv-and-
mod_wsgi/)
|
How to print a reStructuredText node tree?
Question: Section [Parsing the
Document](http://docutils.sourceforge.net/docs/dev/hacking.html#parsing-the-
document) of The [Docutils Hacker's
Guide](http://docutils.sourceforge.net/docs/dev/hacking.html) mentions the
`quicktest.py` utility that can be used to print a node tree representation of
a parsed [reStructuredText](http://docutils.sourceforge.net/rst.html)
document. However I can't find `quicktest.py` anywhere in my docutils
distribution installed in `/usr/lib/python2.7/dist-packages/docutils`. Is
there other way to print the document tree?
Answer: As pointed out by @mzjn the `quicktest.py` script is available at
<https://sourceforge.net/p/docutils/code/HEAD/tree/trunk/docutils/tools/quicktest.py>
A document tree can also be printed as follows:
from docutils.core import publish_string
print publish_string(rst)
where `rst` is a string containing reStructuredText to be processed.
|
python ctype intialising a structure
Question: My structure contains all unsigned char elements
typedef struct
{
unsigned char bE;
unsigned char cH;
unsigned char cL;
unsigned char EId1;
unsigned char EId0;
unsigned char SId1;
unsigned char SId0;
unsigned char DLC;
unsigned char D0;
unsigned char D1;
unsigned char D2;
unsigned char D3;
unsigned char D4;
unsigned char D5;
unsigned char D6;
unsigned char D7;
} CMsg;
The below function calls the structure
extern int WriteCMessage(HANDLE hDev,CMsg* pMsg);
I converted this structure to python ctype
class CMsg(Structure):
_fields_ = [('bE', c_char),
('cH', c_char),
('cL', c_char),
('EId1', c_char),
('EId0', c_char),
('SId1', c_char),
('SId0', c_char),
('DLC', c_char),
('D0', c_char),
('D1', c_char),
('D2', c_char),
('D3', c_char),
('D4', c_char),
('D5', c_char),
('D6', c_char),
('D7', c_char)]
pmsg = CMsg('\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00')
Then i loaded the dll file
hllDll.WriteCANMessage(handle, pmsg)
But this gives error
Error: Access violation at 0x00000000
Answer: You passed `pmsg` by value, but the function expects a pointer. Since you've
initialized to all zeros, the function ends up dereferencing a `NULL` pointer.
Then ctypes uses Windows SEH to route the access violation to a Python
exception.
You need to use `byref(pmsg)` to pass a reference. Also, define the function's
`argtypes` to ensure proper handling of the pointer on 64-bit systems.
from ctypes import *
from ctypes.wintypes import *
class CMsg(Structure):
_fields_ = [
('bE', c_ubyte),
('cH', c_ubyte),
('cL', c_ubyte),
('EId1', c_ubyte),
('EId0', c_ubyte),
('SId1', c_ubyte),
('SId0', c_ubyte),
('DLC', c_ubyte),
('D0', c_ubyte),
('D1', c_ubyte),
('D2', c_ubyte),
('D3', c_ubyte),
('D4', c_ubyte),
('D5', c_ubyte),
('D6', c_ubyte),
('D7', c_ubyte)]
hllDll = cdll...
hllDll.WriteCANMessage.argtypes = [HANDLE, POINTER(CMsg)]
handle = ...
pmsg = CMsg() # initially memset to {0}
hllDll.WriteCANMessage(handle, byref(pmsg))
|
Python Server Socket Without Infinite Loop?
Question: I'd like to create a class that allows sending and receiving on the same port
and create an event-driven application from incoming messages while the
program does it operations. I don't have much experience with sockets so I
don't know how to do this. Here is my SimpleSock class that so far just binds
the socket. I also put an infinite loop in there to listen for connections but
know this won't work for what I want because the program won't be able to do
anything besides listen.
import socket
class SimpleSock:
def __init__(self, ip=None, port=None):
if ip == None or port == None:
print("SimpleSock cannot init without an ip and port")
else:
self.ip = ip
self.port = port
self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print("attempting connection to " + self.ip + " on port " + str(self.port))
self.socket.bind((self.ip, self.port))
self.socket.listen(5)
print("connected")
while True:
(clientsocket, address) = self.socket.accept()
#do something
How can I write a listen without and infinite loop? Do I need to use threads?
Answer: Event-driven network applications in Python can be built using frameworks like
Python Twisted or Tornado. You can see a comparison in another question here:
[When to use Tornado, when to use Twisted / Cyclone / GEvent /
other](http://stackoverflow.com/questions/13941903/when-to-use-tornado-when-
to-use-twisted-cyclone-gevent-other)
The general idea is that the framework will let you register callbacks for
when events happen like data waiting on a socket, and the framework will
usually be your "main loop" (so it takes over control of the main thread
typically). You do not need threads most of the time--everything can be
multiplexed in a single thread so long as all your event sources are waitable
using select() or similar.
|
How to concatenate and convert hex to base 64 in Python?
Question: I'm trying to convert hex values into base 64.
I have a script that does some calculations to each value.
I then want to convert the final values to base 64.
import base64
for i, v in enumerate([0x31, 0x37, 0x32, 0x2e]):
z=i+v #adds positional index to hex value
q=z+0x27 #adds constant
x=q^i # XORs with positional index
print (x)
gives:
> 88
> 94
> 89
> 91
I'm trying to convert these values into base 64. If I manually put them in
this form: `585e595b`, this code is working:
>>> "585e595b".decode('hex').encode('base64')
'WF5ZWw==\n'
Answer: One way to do it:
data = [0x31, 0x37, 0x32, 0x2e]
encoded = base64.b64encode(''.join(hex(x)[2:] for x in data))
|
OpenCV Python unsupported array type error
Question: I am new to Python (but not new to openCV) and I am pretty sure everything is
installed correctly, I have tested some programs and the seem to work fine,
but when ever I want to draw on an image, for example this code taken from a
Python openCV tutorial :
import numpy as np
import cv2
# Create a black image
img = np.zeros((512,512,3), np.uint8)
# Draw a diagonal blue line with thickness of 5 px
img = cv2.line(img,(0,0),(511,511),(255,0,0),5)
cv2.imshow('img',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
I get this following error:
OpenCV Error: Bad flag (parameter or structure field) (Unrecognized or unsupported array type) in cvGetMat, file /build/buildd/opencv-2.3.1/modules/core/src/array.cpp, line 2482
Traceback (most recent call last):
File "/home/dccv/rec 2.py", line 17, in <module>
cv2.imshow('img',img)
cv2.error: /build/buildd/opencv-2.3.1/modules/core/src/array.cpp:2482: error: (-206)
Unrecognized or unsupported array type in function cvGetMat
any help would be appreciated, I get the same error on both windows and
ubuntu.
Answer: `line` function returns `None` so you're trying to show `None`.
The fix (on line 6) is to not set the `img` variable to the return value,
instead just ignore the return value:
import numpy as np
import cv2
# Create a black image
img = np.zeros((512,512,3), np.uint8)
# Draw a diagonal blue line with thickness of 5 px
cv2.line(img,(0,0),(511,511),(255,0,0),5)
cv2.imshow('img',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
|
ctypes: Correctly sublcass c_void_p for passing and returning custom data types, by example
Question: I am working with `ctypes` and cannot seem to figure out how to work with
custom data types. The hope is to have a Python interface to the public
methods of a C++ `cell` class and a C++ `cellComplex` class.
My current problem is working with the C function called
`get_elementsAtSpecifiedDim()`, defined below under `extern "C" {...`. This
function has been written to return a `void *` which is _really_ a
`std:vector< cell<double>* >`, a vector of pointers to C++ `cell` objects.
My Client code below shows an example of a call to this function (via the
Python `CellComplex` method `elemen()`) and this appears to me to be working
fine. You will notice that my Python implementation of `elemen()` declares the
return type `lib.elemen.restype` to be an array of (Python) `Cell` objects.
That's what I get, `>>>print cmplx.elemen()` yields
`[<cellComplex_python.Cell_Array_8 object at 0x10d5f59e0>,
<cellComplex_python.Cell_Array_12 object at 0x10d5f5830>,
<cellComplex_python.Cell_Array_6 object at 0x10d5f58c0>,
<cellComplex_python.Cell_Array_1 object at 0x10d5f5950>]`
**But here's the problem:**
Now I want to call my C functions on one of the `Cell` objects in an array in
this list. For example, `cmplx.elemen()[0][0]` is a `<Cell object at
0x10d5f5b00>`, so in my mind I should be able to do this:
`cmplx.elemen()[0][0].dim()`, **but this segfaults**.
My suspicion is that I am not creating the custom Python classes `Cell` and
`CellComplex` correctly. In particular, in Python class `Cell`, method
`dim(self):` I have the line `lib.dim.argtypes = [Cell]`, which must be
absolutely bogus. As well, I have this silly Python class `c_cellComplex`
which does nothing except allow me to indicate to myself what a particular
`ctypes.c_void_p` is supposed to point to. In fact, I claim that my
definitions of these Python classes are entirely bogus and I am being tricked
into thinking I am on the right track by the miracle that this runs at all (up
until I try to call a `Cell` method on a supposed `Cell` instance...
Client code:
p = [[0,1],[0,1]]
cmplx = cellComplex(p)
e = cmplx.elemen()
e[0][0].dim() # segfault
**begin EDIT** [eryksun's answer
below](http://stackoverflow.com/a/20818377/390433) provides an example of how
to subclass c_void_p, and addresses a few other conceptual issues - start
there if you have the same questions I had.
The segfault issue comes from the fact that `get_elementsAtSpecifiedDim()`
defined in `extern C { ...` returns a memory address to a
`std::vector<cell<double>* >`, a datatype that cannot be parsed back in
Python. In this case I can just grab the pointers in the vector and return
them, like so:
extern "C" {
void * get_elementAtSpecifiedDimAndLoc(void *ptr, int dim, int nr) {
cellComplex<double>* cmplx = static_cast<cellComplex<double>* >(ptr);
cell<double>* c = cmplx->elemen()[dim][nr];
return c;
}
}
and can be called like so:
def elemen(self):
el = []
for i in range(self.dim):
size = lib.size_elementsAtSpecifiedDim(self,i)
cells = []
for j in range(size):
cells.append(lib.get_elementAtSpecifiedDimAndLoc(self,i,j))
el.append(cells)
return el
# put this somewhere
lib.get_elementAtSpecifiedDimAndLoc.restype = Cell
lib.get_elementAtSpecifiedDimAndLoc.argtypes = [CellComplex,c_int,c_int]
**The client code now works.**
**end EDIT**
Here is the magnificent folly:
# cellComplex_python.py
lib = ctypes.cdll.LoadLibrary('./cellComplex_lib.so')
class c_cellComplex(ctypes.c_void_p):
pass
class Cell(ctypes.c_void_p):
def dim(self):
lib.dim.restype = ctypes.c_int
lib.dim.argtypes = [Cell]
self.dimension = lib.dim(self)
return self.dimension
class CellComplex(ctypes.c_void_p):
def __init__(self,p):
self.dimension = len(p)
lib.new_cellComplex.restype = c_cellComplex
lib.new_cellComplex.argtypes = [(ctypes.c_double*2)*self.dimension,
ctypes.c_size_t]
e = [(ctypes.c_double*2)(p[i][0],p[i][1]) for i in range(self.dimension)]
point = ((ctypes.c_double*2)*self.dimension)(*e)
self.cmplx = lib.new_cellComplex(point,self.dimension)
def elemen(self):
lib.size_elementsAtSpecifiedDim.restype = ctypes.c_int
lib.size_elementsAtSpecifiedDim.argtypes = [c_cellComplex,
ctypes.c_int]
lib.get_elementsAtSpecifiedDim.argtypes = [c_cellComplex,ctypes.c_int]
self.sizeAtDim = []
self.elements = []
for i in range(self.dimension+1):
self.sizeAtDim.append(lib.size_elementsAtSpecifiedDim(self.cmplx,i))
lib.get_elementsAtSpecifiedDim.restype = Cell*self.sizeAtDim[i]
self.elements.append(lib.get_elementsAtSpecifiedDim(self.cmplx,i))
return self.elements
`C` code:
// cellComplex_extern.cpp
#include<"cell.hpp">
#include<"cellComplex.hpp">
extern "C" {
void * new_cellComplex(double p[][2], size_t dim) {
std::vector< std::pair<double,double> > point;
for (size_t i=0; i<dim; ++i) {
point.push_back( std::make_pair(p[i][0],p[i][1]));
}
cellComplex<double>* cmplx = new cellComplex<double>(point);
return cmplx;
}
void * get_elementsAtSpecifiedDim(void *ptr, int dim) {
cellComplex<double>* cmplx = static_cast<cellComplex<double>* >(ptr);
std::vector<std::vector<cell<double>* > >* e = &cmplx->elemen();
return &e[dim];
}
int size_elementsAtSpecifiedDim(void *ptr, int dim) {
cellComplex<double>* cmplx = static_cast<cellComplex<double>* >(ptr);
return cmplx->elemen()[dim].size();
}
int dim(void *ptr) {
cell<double>* ref = static_cast<cell<double>* >(ptr);
return ref->dim();
}
}
Answer: Instead of subclassing `c_void_p`, you can define the class method
`from_param` and instance attribute `_as_parameter_`. You may not need either
option if you're just proxying a C++ object that's referenced in a private
attribute such as `_obj`. That said, a subclass of `c_void_p` can be used
directly with ctypes pointers, arrays, and structs, which may be convenient in
your overall design.
The following example may help:
from ctypes import *
__all__ = ['CellComplex']
class Cell(c_void_p):
def __new__(cls, *args, **kwds):
raise TypeError("cannot create %r instances" % cls.__name__)
@property
def dimension(self):
return lib.dim(self)
class CellComplex(c_void_p):
def __init__(self, p):
pair = c_double * 2
point = (pair * len(p))(*(pair(*q[:2]) for q in p))
self.value = lib.new_cellComplex(point, len(p)).value
@property
def dimension(self):
"""Wrap a function that returns size_t."""
return lib.????????(self)
def get_elements(self):
el = []
for i in range(self.dimension):
size = lib.size_elementsAtSpecifiedDim(self, i)
cells = lib.get_elementsAtSpecifiedDim(self, i)
el.append(cells[:size])
return el
Function pointer definitions:
lib = CDLL('./cellComplex_lib.so')
lib.dim.restype = c_int
lib.dim.argtypes = [Cell]
lib.new_cellComplex.restype = CellComplex
lib.new_cellComplex.argtypes = [POINTER(c_double * 2), c_size_t]
lib.size_elementsAtSpecifiedDim.restype = c_int
lib.size_elementsAtSpecifiedDim.argtypes = [CellComplex, c_int]
lib.get_elementsAtSpecifiedDim.restype = POINTER(Cell)
lib.get_elementsAtSpecifiedDim.argtypes = [CellComplex, c_int]
I separated out the function pointer definitions from the class method
definitions. There's no need to redefine a function pointer's `restype` and
`argtypes` every time a method is called. If the function returns a variably
sized array, you're better off setting it to a pointer type. You can slice the
result to a list or `cast` to an array type.
`CellComplex` is initialized by a sequence `p` of floating point pairs such as
`[[0.1, 0.2], [0.3, 0.4], [0.5, 0.6]]`.
I eliminated the `c_cellComplex` class. You can just set the instance's
`value`.
`lib.new_cellComplex` returns an instance of `CellComplex`, but ctypes
bypasses `__new__` and `__init__` when `CellComplex` is used as a `restype`,
so that's not an issue. It would be less twisted to instead override
`__new__`, but you'd still have to override `c_void_p.__init__`.
The `dimension` attribute needs to be a property that calls an exported
function, instead of relying on static data in the Python object.
|
How to properly parse parent/child XML with Python
Question: I have a XML parsing issue that I have been working on for the last few days
and I just can't figure it out. I've used both the ElementTree built-in to
Python as well as the LXML libraries but get the same results. I would like to
continue using ElementTree if I can, but if there are limitations to that
library then LXML would do. Please see the following XML example. What I am
trying to do is find a connection element and see what classes that element
contains. I am expecting each connection to contain at least one class. If it
doesn't have at least one class I want to know that it doesn't. The problem I
am facing is that my code is returning ALL THE CLASSES in the document for
each connection, instead of only the classes for that specific connection.
<test>
<connections>
<connection>
<id>10</id>
<classes>
<class>
<classname>DVD</classname>
</class>
<class>
<classname>DVD_TEST</classname>
</class>
</classes>
</connection>
<connection>
<id>20</id>
<classes>
<class>
<classname>TV</classname>
</class>
</classes>
</connection>
</connections>
</test>
For example, here is my Python code and the output that it returns:
for parentConnection in elemetTree.getiterator('connection'):
# print parentConnection.tag
for childConnection in parentConnection:
# print childConnection.text
if childConnection.tag == 'id':
connID = childConnection.text
print connID
for p in tree.xpath('./connections/connection/classes/class'):
for attrib in p.attrib:
print '@' + attrib + '=' + p.attrib[attrib]
children = p.getchildren()
for child in children:
print child.text
Here is the output:
10
DVD
DVD_TEST
TV
20
DVD
DVD_TEST
TV
As you can see, I am printing out the text of the CONNECTION ID and then the
text for each CLASSNAME. However, as you can see, they both contain the same
text for CLASSNAME. The output should really look like this:
10
DVD
DVD_TEST
20
TV
Now as the above hand modified example shows each connection ID (Parent) has
the appropriate classes/classnames (children). I just can't figure out how to
make this work. If any of you have the knowledge to make this work, I would
love to hear it.
I've tried building a data structure and other examples on this forum but just
can't get it to work right.
Answer: My solution without using _xpath._ What I recommend is digging a little
further into **lxml** documentation. There might be more elegant and direct
ways to achieve this. There's a lot to explore!.
**Solution:**
from lxml import etree
from io import BytesIO
class FindClasses(object):
@staticmethod
def parse_xml(xml_string):
parser = etree.XMLParser()
fs = etree.parse(BytesIO(xml_string), parser)
fstring = etree.tostring(fs, pretty_print=True)
element = etree.fromstring(fstring)
return element
def find(self, xml_string):
for parent in self.parse_xml(xml_string).getiterator('connection'):
for child in parent:
if child.tag == 'id':
print child.text
self.find_classes(child)
@staticmethod
def find_classes(child):
for parent in child.getparent(): # traversing up -> connection
for children in parent.getchildren(): # children of connection -> classes
for child in children.getchildren(): # child of classes -> class
print child.text
print
if __name__ == '__main__':
xml_file = open('foo.xml', 'rb') #foo.xml or path to your xml file
xml = xml_file.read()
f = FindClasses()
f.find(xml)
**Output:**
10
DVD
DVD_TEST
20
TV
|
Executing a shell script in Python from the JSON document
Question: I am trying to execute the shell script in Python using subprocess module.
Below is my shell script which is called as `testing.sh`.
#!/bin/bash
hello=$jj1
echo $hello
echo $jj1
echo $jj2
for el1 in $jj3
do
echo "$el1"
done
for el2 in $jj4
do
echo "$el2"
done
Now I am trying to execute the above shell script in Python so I did like this
-
subprocess.call(['./testing.sh'])
and it works fine. Now I am thinking to add the above script in a JSON
document like this and then execute it -
json_script = '{"script":"above testing.sh script here"}'
j = json.loads(json_script)
shell_script = j['script']
subprocess.call(shell_script, shell=True)
But everytime I am trying, it is giving me an error -
Below is my full Python script which contains the above `testing.sh` shell
script in a JSON document -
#!/usr/bin/python
import subprocess
import json
import socket
import os
jsonData = '{"pp": [0,3,5,7,9], "sp": [1,2,4,6,8]}'
jj = json.loads(jsonData)
print jj['pp']
print jj['sp']
os.putenv( 'jj1', 'Hello World 1')
os.putenv( 'jj2', 'Hello World 2')
os.putenv( 'jj3', ' '.join( str(v) for v in jj['pp'] ) )
os.putenv( 'jj4', ' '.join( str(v) for v in jj['sp'] ) )
print "start"
jsonDataaa = '{"script":"#!/bin/bash \\n hello=$jj1 \\n echo $hello \\n echo $jj1 \\n echo $jj2 \\n for el1 in $jj3 \\n do \\n echo "$el1" \\n done \\n for el2 in $jj4 \\n do \\n echo "$el2" \\n done"}'
j = json.loads(jsonDataaa)
shell_script = j['script']
print "start"
subprocess.call(shell_script, shell=True)
print "end"
And below is the error I am getting -
File "C:\Python27\lib\json\__init__.py", line 338, in loads
return _default_decoder.decode(s)
File "C:\Python27\lib\json\decoder.py", line 365, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "C:\Python27\lib\json\decoder.py", line 381, in raw_decode
obj, end = self.scan_once(s, idx)
ValueError: Expecting , delimiter: line 1 column 113 (char 112)
And the expected output I should be getting like this -
[0, 3, 5, 7, 9]
[1, 2, 4, 6, 8]
start
Hello World 1
Hello World 2
0
3
5
7
9
1
2
4
6
8
end
**UPDATE:-**
If I have my jsonDataaa like this
jsonDataaa = '{"script":"#!/bin/bash \\n hello=$jj1 \\n echo $hello \\n echo $jj1 \\n echo $jj2 \\n"}'
then it works fine... And I am able to execute it properly.. But if my
jsonDataaa is as I mentioned in my question, then only it gives me an error. I
am thinking there might be some syntax error which I am not able to
understand.
Answer: It gives you this error because your json string is invalid. Specifically, it
contains unescaped quotes.
It works if you replace your jsonDataaa assignment with:
jsonDataaa = '{"script":"#!/bin/bash \\n hello=$jj1 \\n echo $hello \\n echo $jj1 \\n echo $jj2 \\n for el1 in $jj3 \\n do \\n echo \\"$el1\\" \\n done \\n for el2 in $jj4 \\n do \\n echo \\"$el2\\" \\n done"}'
|
Calling variables from inside functions in Python
Question: I know I have already asked a question like this before but I have made my
code much cleaner and I am still coming up with a problem.
My code goes like this:
class Email_Stuff:
def Get_From_Email():
#code to open up window and get email address
emailaddr = #the input
return emailaddr
def Get_To_Email():
#code to open up window and get to email address
recipaddr = #the input
return recipaddr
def Get_Email_Address():
#code to open up window and get email username
EmailUser = #the input
return EmailUser
def Get_Email_Password():
#code to open up window and get email password
EmailPass = #the input
return EmailPass
def Send_Email():
import smtplib
server = smtplib.SMTP('smtp.gmail.com', 587)
server.login((EmailUser),(EmailPass))
message = "Python Test Email"
server.sendmail(emailaddr,recipaddr,message)
I need to get the variables: `emailaddr`, `recipaddr`, `EmailUser`, and
`EmailPass` into the function `Send_Email`. I'm not sure how I could do that
though because when I run this code, it tells me that "the global name isn't
defined".
Any ideas?
Answer: Make emailaddr, recipaddr, EmailUser, and EmailPass become instance variables
by adding prefix "self.".
class Email_Stuff():
def Get_From_Email(self):
#code to open up window and get email address
self.emailaddr = #the input
def Get_To_Email(self):
#code to open up window and get to email address
self.recipaddr = #the input
def Get_Email_Address(self):
#code to open up window and get email username
self.EmailUser = #the input
def Get_Email_Password(self):
#code to open up window and get email password
self.EmailPass = #the input
def Send_Email(self):
import smtplib
server = smtplib.SMTP('smtp.gmail.com', 587)
server.login((self.EmailUser),(self.EmailPass))
message = "Python Test Email"
server.sendmail(self.emailaddr,self.recipaddr,self.message)
instance = Email_Stuff()
instance.Get_From_Email()
instance.Get_To_Email()
instance.Get_Email_Address()
instance.Get_Email_Password()
instance.Send_Email()
BTW, name of methods should be lowercase.
|
I want to download code from Google App Engine
Question: I want to update the app in google app store. But I can't download the code...
Is there any way to update the app without downloading the code?
I tried to download with python, google app engine SDK...
But appcfg.py download_app -A
This command does not work giving this error
NameError: global name 'execfile' is not defined...
Can you help me with this?
Answer: The error you have shown may occur due to incorrect PYTHONPATH environment
variable.
If you are using the Windows version of the GAE SDK, then do the following:
1) Go to Edit > Preferences
2) Correct your Python Path.
To know the Python Path in windows do the following in the Python IDLE or
Python CMD:
import os
import sys
print os.path.dirname(sys.executable)
For downloading your source code try this:
download_app -A app_name -V version C:\path_to_project
You may or may not need to escape the backslash.
Replace app_name, version and C:\path_to_project with appropriate values
To know the version go to the app engine admin website
[appengine.appspot.com](http://appengine.appspot.com)
|
Placing the legend outside the plot
Question: I want to position the legend outside the drawing box. I do not find a clean
way to do this. The main problem is having everything fit on the file saved.
The only thing I have been able to figure out is this code:
#! /usr/bin/python
import matplotlib
# matplotlib.use('pdf')
from matplotlib.pyplot import *
subplot(111)
plot([1,2,3], label="test1")
l=legend(bbox_to_anchor=(1.05, 1), loc=2,borderaxespad=0)
tight_layout(rect=(0,0,0.8,1))
savefig('test.pdf')
There are a couple of caveats:
1. The tight_layout seems to be incompatible with `matplotlib.use('pdf')`
2. The 0.8 in the `tight_layout` has been found by trials and errors. If I replace `label="test"` by `label="this is a very very long test"`, the legend will once again get out of the border of the file. I would like that to be adjusted automatically. I have not been able to retrieve the size of the legend. `l.get_frame().get_width()` seems to always return 1.0.
3. The `tight_layout` changes the size of the plot. What I would like to achieve is: specify the size of the plot in cm (or in inches). Placing the legend outside the plot. Having a file with the correct size in order that everything fits in, including the legend; without having to resort to trial and errors.
Answer: You can look at the answer to
[this](http://stackoverflow.com/questions/4700614/how-to-put-the-legend-out-
of-the-plot) question by [Joe
Kington](http://stackoverflow.com/users/325565/joe-kington). The answer
describes most of the options you can play around with regarding placement of
legends.
|
Best and/or fastest way to create lists in python
Question: In python, as far as I know, there are at least 3 to 4 ways to create and
initialize lists of a given size:
**Simple loop with`append`:**
my_list = []
for i in range(50):
my_list.append(0)
**Simple loop with`+=`:**
my_list = []
for i in range(50):
my_list += [0]
**List comprehension:**
my_list = [0 for i in range(50)]
**List and integer multiplication:**
my_list = [0] * 50
In these examples I don't think there would be any performance difference
given that the lists have only 50 elements, but what if I need a list of a
million elements? Would the use of `xrange` make any improvement? Which is the
preferred/fastest way to create and initialize lists in python?
Answer: Let's run some time tests* with
[`timeit.timeit`](http://docs.python.org/2/library/timeit.html#timeit.timeit):
>>> from timeit import timeit
>>>
>>> # Test 1
>>> test = """
... my_list = []
... for i in xrange(50):
... my_list.append(0)
... """
>>> timeit(test)
22.384258893239178
>>>
>>> # Test 2
>>> test = """
... my_list = []
... for i in xrange(50):
... my_list += [0]
... """
>>> timeit(test)
34.494779364416445
>>>
>>> # Test 3
>>> test = "my_list = [0 for i in xrange(50)]"
>>> timeit(test)
9.490926919482774
>>>
>>> # Test 4
>>> test = "my_list = [0] * 50"
>>> timeit(test)
1.5340533503559755
>>>
As you can see above, the last method is the fastest by far.
* * *
However, it should _only_ be used with immutable items (such as integers).
This is because it will create a list with references to the same item.
Below is a demonstration:
>>> lst = [[]] * 3
>>> lst
[[], [], []]
>>> # The ids of the items in `lst` are the same
>>> id(lst[0])
28734408
>>> id(lst[1])
28734408
>>> id(lst[2])
28734408
>>>
This behavior is very often undesirable and can lead to bugs in the code.
If you have mutable items (such as lists), then you should use the still very
fast list comprehension:
>>> lst = [[] for _ in xrange(3)]
>>> lst
[[], [], []]
>>> # The ids of the items in `lst` are different
>>> id(lst[0])
28796688
>>> id(lst[1])
28796648
>>> id(lst[2])
28736168
>>>
* * *
*Note: In all of the tests, I replaced `range` with `xrange`. Since the latter returns an iterator, it should always be faster than the former.
|
Python memory management for variables
Question: I have a question regarding python memory management. I have the following
code
def operation(data):
#some manipulations on data
result=something.do(data)
#some manipulations on result
return result
Now I am calling this function `operation` many times (probably like more than
200 times). Does python use a same memory for the `result` variable everytime
I call `operation`? As in `C` we can use `Malloc` to allocate memory once and
use to the same memory inorder to avoid fragmentation.
Answer: The whole point of high-level languages like Python is that they free you from
having to worry about memory management. If exact control over memory
allocation is important to you, you should write C. If not, you can write
Python.
As most Python programmers will tell you from their experience, manual memory
management isn't nearly as important as you think it is.
|
Relationship between (1) hash function, (2) length of signature and (3) jaccard similarity?
Question: I am trying to understand/implement minHash based jaccard similarity in
python. The main goal is use it in MapReduce. However I am not clear how the
choice of hash function and length of signature affects error rate in
computing jaccard similarity. From wikipedia, I found that in general length
of signature (K) and error (e) associated with the computed jaccard similarity
is k = O(1/e^2). I tried implementing minHash in python:
import random
import sys
#ERROR_THRESHOLD = 0.05
#SIG_LENGTH = int(1/(ERROR_THRESHOLD**2))
_memomask = {}
def hash_values(n, x):
"""Compute n different hash values"""
values = []
for i in range(n):
mask = _memomask.get(i)
if mask is None:
random.seed(i)
mask = _memomask[i] = random.getrandbits(32)
values.append((hash(str(x)) % mask))
return values
def compare_signatures(x, y):
"""Compare MinHash Signatures"""
size = len(x)
if size != len(y): raise Exception("Different signature length")
if size == 0: raise Exception("signature length is zero")
counter = 0
for i in range(size): counter += int(x[i] == y[i])
return counter/float(size)
items = [['A',3], ['A',6], ['A',9], ['B',2], ['B',4], ['B',6], ['B',8]]
for SIG_LENGTH in [1, 10, 100, 400, 1000]:
#Step 1: Compute Hash Signature for each token
data = []
for item in items:
values = hash_values(SIG_LENGTH, item[1])
key = item[0]
data.append((key, values))
#Step 2: Group by Key and compute MinHash for each index
signatures = {}
for item in data:
key = item[0]
values = item[1]
if key not in signatures: signatures[key] = [-1.0]*SIG_LENGTH
cur_signature = signatures[key]
signatures[key] = [(values[i] if cur_signature[i] == -1.0 else min(values[i], cur_signature[i])) for i in range(SIG_LENGTH)]
#Step 3: Compute Probability of minHash signature to be same
keys = signatures.keys()
key_length = len(keys)
print "Jaccard Similarity based on signature of length {0}".format(SIG_LENGTH)
for i in range(key_length):
x_key = keys[i]
x_sig = signatures[x_key]
for j in range(i+1,key_length):
y_key = keys[j]
y_sig = signatures[y_key]
print "J({0},{1}) = {2}".format(x_key, y_key, compare_signatures(x_sig, y_sig))
In my test, I found that accuracy increases as the length of signature
increases but then it starts decreasing (or remains stable) thereafter. I am
wondering is it because of the choice of hash function. If yes, can someone
please suggest a good hash function to use.
I found some related post but still not clear: [How many hash functions are
required in a minhash
algorithm](http://stackoverflow.com/questions/19701052/how-many-hash-
functions-are-required-in-a-minhash-algorithm/20820889#20820889)
Answer: md5 and sha work pretty well:
import random
import hashlib
import sys
k = int(sys.argv[1])
salts = [random.getrandbits(32) for i in range(k)]
def h(value, salt):
m = hashlib.md5() #or hashlib.sha1()
m.update(str(value))
m.update(str(salt))
return m.digest()
def get_signatures(A):
return [min([h(x, salt) for x in A]) for salt in salts]
def compare_signatures(A, B):
"""Compare MinHash Signatures"""
sigA = get_signatures(A)
sigB = get_signatures(B)
return sum(map(lambda x: int(sigA[x] == sigB[x]), range(k)))/float(k)
A = [3,6,9]
B = [2,4,6,8]
print compare_signatures(A, B)
and some tests:
$ for((i=10;i<2000;i*=10)); do python minhash.py $i; done
0.2
0.14
0.163
|
why is the python GUI interface fleeting
Question:
#coding=utf-8
import wx
class App(wx.App):
def OnInit(self):
frame=wx.Frame(parent=None,title='Bare')
frame.Show()
return Ture
app=App()
app.MainLoop()
runs OK! but the GUI interface is fleeting, just leaving the CMD console in
the screen. a newer for python ,why the outcome of the GUI interface fleeting?
environment:Gvim+WIN7+PYTHON2.7
Answer: First, according to `help :!` command of `vim`:
> `:!{cmd}` Execute {cmd} with **the shell**.
`vim` cause the cmd shell to be executed.
Second, according to [Using Python on Windows - Executing
scripts](http://docs.python.org/2/using/windows.html#executing-scripts):
> Python scripts (files with the extension .py) will be executed by
> `python.exe by` default. **This executable opens a terminal, which stays
> open even if the program uses a GUI.** If you do not want this to happen,
> use the extension `.pyw` which will cause the script to be executed by
> `pythonw.exe` by default (both executables are located in the top-level of
> your Python installation directory). This suppresses the terminal window on
> startup.
So, if you want run the GUI program without cmd console, run the program
outside the vim using `pythonw.exe`. For instance, save the file with `.pyw`
extension, and double click the file.
|
Numbers without remainder python
Question: I need to print out numbers between 1 and n(n is entered with keyboard) that
do not divide by 2, 3 and 5. I need to use while or for loops and the
remainder is gotten with %. I'm new here and I just don't understand the usage
of %? I tried something like this:
import math
print("Hey. Enter a number.")
entered_number = int(input())
for i in range(1, entered_number):
if i%2 != 0:
print("The number", i, "is ok.")
else:
pass
if i%3 != 0:
print("The number", i, "is ok.")
else:
pass
if i%5 != 0:
print("The number", i, "is ok.")
help?
Answer: You need to test for all 3 conditions in **one** statement, not in 3:
for i in range(1, entered_number):
if i % 2 != 0 and i % 3 != 0 and i % 5 != 0:
print("The number", i, "is ok.")
The `and` operators here make sure that _all three_ conditions are met before
printing.
You are testing each condition in isolation, which means that if the number
is, say, 10, you are still printing `The number 10 is ok.` because it is not
divisible by 3. For numbers that _are_ okay, you were printing `The number ...
is ok.` 3 times, as your code tests that it is not divisible by 3 different
numbers separately, printing each time.
|
global name 'GLib2Reactor' is not defined
Question: I'm struggling to get some python code using the python-brisa framework to
work, the code is not written by me but should be straight forward.
from brisa.core.reactors import install_default_reactor
reactor = install_default_reactor()
from brisa.core.threaded_call import run_async_function
import xml.etree.ElementTree as ET
from time import sleep
import sys, os
import sonos
import knx
Howewer after installing the frameworks I get
Traceback (most recent call last):
File "knxsonos.py", line 24, in <module>
reactor = install_default_reactor()
File "/usr/local/lib/python2.7/dist-packages/brisa/core/reactors/__init__.py", line 14, in install_default_reactor
return GLib2Reactor()
NameError: global name 'GLib2Reactor' is not defined
I have been looking both stack overflow, and googling for days without finding
a solution.
Anyone??, help would be greatly appreciated...
Answer: Here's some possibilities:
* **GLib2Reactor doesn't return anything** \- Then your code is wrong
* **GLib2Reactor is not declared** \- try this:
`x = GLib2Reactor()`
`return x`
* **GLib2Reactor has to be imported** \- just import it
**my best advice:** read the docs
|
Python: correct way to pass objects between modules
Question: I am following the [Flask SQLalchemy
Quickstart](http://pythonhosted.org/Flask-SQLAlchemy/quickstart.html) which
has all of the code in a single file:
Here is my initial **index.py** :
from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
db = SQLAlchemy(app)
# [snip] - some classes related to SQLAlchemy are here
if __name__ == '__main__':
app.run(host='0.0.0.0')
I want to split the code up a bit, so I created a separate file called
**database.py** which will contain all of the database related code, and be
imported as a module.
I modified my **index.py** to look like this:
from flask import Flask
# Import my database module
import database
app = Flask(__name__)
if __name__ == '__main__':
app.run(host='0.0.0.0')
And the file **database.py** :
from flask.ext.sqlalchemy import SQLAlchemy
app.config['SQLALCHEMY_DATABASE_URI]'] = 'sqlite:////tmp/test.db'
db = SQLAlchemy(app)
# [snip] - some classes related to SQLAlchemy are here
Obviously when I try to run this code I get the following error:
File "database.py", line 5, in <module>
app.config['SQLALCHEMY_DATABASE_URI]'] = 'sqlite:////tmp/test.db'
NameError: name 'app' is not defined
I can see that this is because the `app` object only exists within the parent
module.
I could put the following lines back into **index.py** :
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
db = SQLAlchemy(app)
But this creates a similar problem, whereby `db` is not available within the
database.py file.
What is the correct way to code this?
Answer: Edited answer after comment:
Simply use
from index import app
in database.py.
Alternatively, with the
import index
statement, use `index.app` instead of `app` only.
This should help you get out of python's import hell.
Btw: Not sure which IDE you are using. I like pycharm a lot. Using it you can
refactor code and issues such as above are prevented automagically.
|
Is there a way to have a python program run an action when it's about to crash?
Question: I have a python script with a loop that crashes every so often with various
exceptions, and needs to be restarted. Is there a way to run an action when
this happens, so that I can be notified?
Answer: You could install an exception hook, by assigning a custom function to the
[`sys.excepthook`
handler](http://docs.python.org/2/library/sys.html#sys.excepthook). The
function is called whenever there is a _unhandled_ exception (so one that
exits the interpreter).
import sys
def myexcepthook(type, value, tb):
import traceback
from email.mime.text import MIMEText
from subprocess import Popen, PIPE
tbtext = ''.join(traceback.format_exception(type, value, tb))
msg = MIMEText("There was a problem with your program:\n\n" + tbtext)
msg["From"] = "[email protected]"
msg["To"] = "[email protected]"
msg["Subject"] = "Program exited with a traceback."
p = Popen(["/usr/sbin/sendmail", "-t"], stdin=PIPE)
p.communicate(msg.as_string())
sys.excepthook = myexcepthook
This exception hook emails you the traceback whenever the program exits,
provided you have a working `sendmail` command on your system.
|
Tkinter with Python 3.3 : Change colour of button on click
Question: So I have been playing with tkinter to try add a gui to a lift simulator
project I have written for university. It is not really needed, but I would
like to add it.
Here is the code that I currently have.
import tkinter as tk
class Application(tk.Frame):
def __init__(self, master=None):
tk.Frame.__init__(self, master)
master.title("Test") #Controls the window title.
self.pack()
self.createWidgets()
def createWidgets(self):
floors = [i for i in range(41)]
buttons = []
xPos = 0
yPos = 0
for floor in floors:
if(yPos == 5):
xPos = xPos + 1
yPos = 0
if(xPos == 8):
yPos = 2
self.button = tk.Button(self, width=3, text=floor,
command = lambda f=floor: self.pressed(f))
self.button.grid(row=xPos, column =yPos)
yPos = yPos +1
self.QUIT = tk.Button(self, text="QUIT", fg="red",
command=root.destroy).grid(row = xPos, column = yPos)
def pressed(self, index):
print("number pressed", index)
self.button.configure(bg = "red")
root = tk.Tk()
app = Application(master=root)
app.mainloop()
This is all fine and dandy other than when the button is pressed it prints out
the correct number, but it changes the background of the last button (number
40) to red, not the one pressed.
If you could let me know what needs correcting that would be great.
Thanks
Answer: `self.button` can only ever reference a single button, and it will always be
whatever was assigned to it last. A simple solution is to store the button
references in a dict, using `floor` as the key. Since you're passing that to
the callback, you then have everything you need to reconfigure the button:
def createWidgets(self):
...
self.buttons = {}
for floor in floors:
...
self.buttons[floor] = tk.Button(...)
...
def pressed(self, index):
...
self.buttons[index].configure(bg="red")
|
Python PXSSH GUI spawn on login failure
Question: I can't stop the GUI from spawning when a login failure occurs.
simple example that fails and spawns a GUI.
>>> import pxssh
>>>
>>> ssh = pxssh.pxssh()
>>> ssh.force_password = True
>>> ssh.login('127.0.0.1', 'root', 'falsePW')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.7/dist-packages/pxssh.py", line 226, in login
raise ExceptionPxssh ('password refused')
pxssh.ExceptionPxssh: password refused
>>>
I have tried disabling x11 forwarding in these files, nothing changed.
`/etc/ssh/ssh_config` `/etc/ssh/sshd_config`
I have also tried going into the pxssh module and where it sets the ssh
options I set the flag `-x Disables X11 forwarding.` still no change.
I am running cinnamon on Linux Mint, the pxssh docs said some x display
managers will start up a GUI. To solve this is says to remove all ssh-agents,
which I have also tried to no avail.
Answer: After tampering with the `pxssh.py` module I found a solution thats very
simple.
inside the pxssh.py module: `sudo nano /usr/lib/python2.7/dist-
packages/pxssh.py`
Location Update: `sudo nano /usr/lib/python2.7/dist-packages/pexpect/pxssh.py`
class pxssh(spawn)
def _init__( parameters )
# change these variables to shown value
self.force_password = True
self.auto_prompt_reset = False
# next under the login function
def login( parameters )
# set the -x flag: disables x11 forwarding (removing GUI)
ssh_options = '-q -x'
|
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