import csv
import numpy as np
import random  # Import the random module

def change_fourth_occurrence(matrix):
    for col in range(len(matrix[0])):
        count = 1
        for row in range(1, len(matrix)):
            if matrix[row][col] == matrix[row - 1][col]:
                count += 1
            else:
                count = 1

            if count == 4:
                current_number = matrix[row][col]
                
                # Generate a random number within the range [current_number-1, current_number+1]
                next_number = random.choice([current_number - 1, current_number + 1])

                matrix[row][col] = next_number
                count = 1

    # Post-processing: Ensure there are no negative numbers in the matrix
    matrix[matrix < 0] = 0

# Read the matrix from CSV
input_matrix = []
with open('matrix2.csv', 'r') as file:
    csv_reader = csv.reader(file)
    for row in csv_reader:
        input_matrix.append([int(num) for num in row])

# Convert the matrix to a NumPy array for easy column indexing
input_matrix = np.array(input_matrix)

# Call the function to modify the matrix
change_fourth_occurrence(input_matrix)

# Write the modified matrix back to CSV
with open('matrix5.csv', 'w', newline='') as file:
    csv_writer = csv.writer(file)
    csv_writer.writerows(input_matrix)