Python updating list when I don't want it to

Question

first time on stack overflow. I am very new to python and programming in general.

This particular function is supposed to take 3 matrices as inputs: two N x 1 matrices and an N x N matrix. Using one of the matrices, it is supposed to sort all values of 1 to the top, and all values of 0 to the bottom. This works fine. The N x N matrix is supposed to swap columns that correspond to the rows that were swapped in the N x 1 matrix: ie if rows 3 and 4 are swapped in the N x 1 matrix, then columns 3 and 4 need to be swapped in the N x N matrix.

The issue is that, in the inner for loop, it seems to be updating the values of the variables as soon as the k_bar matrix (N x N) is changed, which causes all columns to have the same value in every row by the end of the iterations. I have no idea how to stop this, or why it is doing it.

If I print out the values immediately before and after the lines k_bar[0][k, (i + 1)] = temp_left[0][k] and k_bar[0][k, i] = temp_right[0][k] as it loops through the inner for loop, it prints array([1, 4, 7]) array([2, 5, 8]) and then on the next iteration it prints array([1, 4, 7]) array([1, 5, 8]) and keeps going until both read array([1, 4, 7]) .

Any help is appreciated.

Here is my code:

import numpy as np
def reorder(r, k_bar, f):
    import numpy as np

    num_react = 0

    for i in range(len(r)):
        if r[i][0] == 0:
            pass

        else:
            num_react += 1

    consecutive_count = 0

    while(consecutive_count != num_react):

        for i in range(len(r) - 1):
            if r[i][0] == 0:
                temp_above = r[i][0]
                temp_below = r[i + 1][0]
                r[i][0] = temp_below
                r[i + 1][0] = temp_above

                temp_above2 = f[i][0]
                temp_below2 = f[i + 1][0]
                f[i][0] = temp_below2
                f[i + 1][0] = temp_above2

                temp_left = []
                temp_left.append(k_bar[0][:, i])
                temp_right = []
                temp_right.append(k_bar[0][:, (i + 1)])

                for k in range(len(r)):
                    k_bar[0][k, (i + 1)] = temp_left[0][k]
                    k_bar[0][k, i] =  temp_right[0][k]

            else:
                consecutive_count += 1

                if consecutive_count == len(r) and consecutive_count != num_react:
                    consecutive_count = 0

    print(r)
    print(k_bar)
    print(f)

ke = []
fe = []
re = []

ke.append(np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]], dtype = int))
fe.append(np.array([0], dtype = int))
fe.append(np.array([0], dtype = int))
fe.append(np.array([1], dtype = int))
re.append(np.array([0], dtype = int))
re.append(np.array([0], dtype = int))
re.append(np.array([1], dtype = int))

print(ke, fe, re)

reorder(re, ke, fe)

Answer 1

I figured it out. The temp_left and temp_right were being considered as the same list as k_bar. Used temp_left.append(k_bar[0][:, i].copy()) and it worked fine.