Remove all zero rows and columns in one go in Python

Question

I want to remove all zero rows and columns in one line from the array A1. I present the current and expected outputs.

import numpy as np

A1=np.array([[0, 0, 0],
            [0, 1, 2],
            [0, 3, 4]])

A1 = A1[~np.all(A1 == 0, axis=0)]
print([A1])

The current output is

[array([[0, 1, 2],
       [0, 3, 4]])]

The expected output is

[array([[1, 2],
        [3, 4]])]

Are you sure the example outputs are from the same A1 matrix? I don't see 2 and 4 in there. — ats
– ats, Commented Feb 9, 2023 at 6:57

Hadar · Accepted Answer · 2023-02-09 09:42:33Z

3

Not really sure your example works, but given the description in the title - for a matrix matrix, you can use

mask = matrix != 0
new_matrix = matrix[np.ix_(mask.any(1), mask.any(0))]

you can check out this post about np.ix_

answered Feb 9, 2023 at 7:06

Hadar

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