Interleaving function not producing expected results

Question

I am trying to make a function to interleave a binary list into an array. The matrix size is 10 rows x 9 columns, initialized to None. The bits are fed into the matrix one at a time, with the first input bit being fed into (0,0). The bits are fed into (previous row + 7) mod 10, and when the column is full, the column is moved to the right, and the column 0 is filled with the next set of bits. However, I am running into a problem with the column fill loop. Every row in column zero is being set to the same value!

Here is what I have so far:

>>> row = 0
>>> interleave_row = [None,None,None,None,None,None,None,None,None]
>>> interleave_matrix = [interleave_row,interleave_row,interleave_row,interleave_row,interleave_row,interleave_row,interleave_row,interleave_row,interleave_row,interleave_row]

This yields a matrix that looks like:

    [None, None, None, None, None, None, None, None, None],
    [None, None, None, None, None, None, None, None, None],
    [None, None, None, None, None, None, None, None, None],
    [None, None, None, None, None, None, None, None, None],
    [None, None, None, None, None, None, None, None, None],
    [None, None, None, None, None, None, None, None, None],
    [None, None, None, None, None, None, None, None, None],
    [None, None, None, None, None, None, None, None, None],
    [None, None, None, None, None, None, None, None, None]]

>>> input = [0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0]
>>> for i in range(0,10):
        interleave_matrix[row][0] = input[i]
        row = (row+7)%10

This yields:

    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None]]

It should look like this:

    [0, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [0, None, None, None, None, None, None, None, None],
    [0, None, None, None, None, None, None, None, None],
    [0, None, None, None, None, None, None, None, None],
    [0, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None],
    [1, None, None, None, None, None, None, None, None]]

Am I having a noob moment? I know the row increment is working fine, as I've looped it by itself. What could be causing such weird behaviour?

EDIT: I just tried looping through the first four bits (guaranteed to end on a 0 bit), and it's not setting the entire row to the bit, it's just setting the entire row to 1. It's getting more and more strange...

Your matrix actually contains N references to the same column. So when you modify a value in one column, this value is also modified in all other columns. Consider creating matrix another way to make independent columns: https://stackoverflow.com/q/2397141/6131611 https://stackoverflow.com/q/6667201/6131611 — Pavel, May 02 '20 at 16:36
It works! Was definitely a noob moment >~> I'm upset this wasn't an answer so I could mark it! — William Trammell, May 02 '20 at 16:59

score 0 · Accepted Answer · answered May 02 '20 at 19:43

Answer posted by Pavel!

Your matrix actually contains N references to the same column. So when you modify a value in one column, this value is also modified in all other columns. Consider creating matrix another way to make independent columns: stackoverflow.com/q/2397141/6131611 stackoverflow.com/q/6667201/6131611

It was definitely a noob moment, but I got to learn from it! Thank you!

Interleaving function not producing expected results

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