python - increase array size and initialize new elements to zero

Question

I have an array of a size 2 x 2 and I want to change the size to 3 x 4.

A = [[1 2 ],[2 3]]
A_new = [[1 2 0 0],[2 3 0 0],[0 0 0 0]]

I tried

Answer 1

Pure Python way achieve this:

row = 3
column = 4
A = [[1, 2],[2, 3]]

A_new = map(lambda x: x + ([0] * (column - len(x))), A + ([[0] * column] * (row - len(A))))

then A_new is [[1, 2, 0, 0], [2, 3, 0, 0], [0, 0, 0, 0]].

Good to know:

• [x] * n will repeat x n-times
• Lists can be concatenated using the + operator

Explanation:

• map(function, list) will iterate each item in list pass it to function and replace that item with the return value
• A + ([[0] * column] * (row - len(A))): A is being extended with the remaining "zeroed" lists
  • repeat the item in [0] by the column count
  • repeat that array by the remaining row count
• ([0] * (column - len(x))): for each row item (x) add an list with the remaining count of columns using