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import math
import torch
import torch.nn as nn
class ConcatEdgeEncoder(nn.Module):
def __init__(self, state_dim, emb_dim, dropout):
super().__init__()
self.state_dim = state_dim
self.emb_dim = emb_dim
self.norm_factor = 1 / math.sqrt(emb_dim)
# initial embedding for state
if state_dim > 0:
self.init_linear_state = nn.Linear(state_dim, emb_dim)
# out linear layer
self.out_linear = nn.Linear((2 + int(state_dim > 0)) * emb_dim, emb_dim)
# Dropout
self.dropout = nn.Dropout(dropout)
self.reset_parameters()
def reset_parameters(self):
for param in self.parameters():
stdv = 1. / math.sqrt(param.size(-1))
param.data.uniform_(-stdv, stdv)
def forward(self, inputs, node_emb):
"""
Paramters
---------
inputs: dict
curr_node_id: torch.LongTensor [batch_size]
next_node_id: torch.LongTensor [batch_size]
mask: torch.LongTensor [batch_size x num_nodes]
state: torch.FloatTensor [batch_size x state_dim]
node_emb: torch.tensor [batch_size x num_nodes x emb_dim]
node embeddings obtained from the node encoder
Returns
-------
h: torch.tensor [batch_size x emb_dim]
edge embeddings
"""
curr_node_id = inputs["curr_node_id"]
next_node_id = inputs["next_node_id"]
state = inputs["state"]
batch_size = curr_node_id.size(0)
#--------------------------------
# generate queries, keys, values
#--------------------------------
node_emb = self.dropout(node_emb)
curr_emb = node_emb.gather(1, curr_node_id[:, None, None].expand(batch_size, 1, self.emb_dim))
next_emb = node_emb.gather(1, next_node_id[:, None, None].expand(batch_size, 1, self.emb_dim))
if state is not None and self.state_dim > 0:
state_emb = self.init_linear_state(state) # [batch_size x emb_dim]
edge_emb = torch.cat((curr_emb, next_emb, state_emb[:, None, :]), -1) # [batch_size x 1 x (3*emb_dim)]
else:
edge_emb = torch.cat((curr_emb, next_emb), -1) # [batch_size x 1 x (2*emb_dim)]
edge_emb = edge_emb.squeeze(1) # [batch_size x (2*emb_dim)]
return self.out_linear(edge_emb) |