How to enlarge a numpy array

Question

I have a 2D numpy array

import numpy as np
np.array([[1, 2], [3, 4]])

[[1 2]
 [3 4]]

I would like the above array to be enlarged to the following:

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

[[1 1 2 2]
 [1 1 2 2]
 [3 3 4 4]
 [3 3 4 4]]

Each element in the original array because a 2x2 array in the new array.

I do I go from the first array to the second 'enlarged' array?

Edit

This is different from the question about scaling here How to "scale" a numpy array? because np.kron(a, np.ones((2,2))) is not the same as a.repeat(2, axis=1).repeat(2, axis=0)

Edit #2 still waiting to get the [duplicate] flag removed

As posted by @Michael Szczesny. The numpy API has seen a slight change. This question is relevant as updated answers are being provide.

It was. I don't know when it changed. You can use np.ones((2,2), 'bool'). — Michael Szczesny
– Michael Szczesny, Commented Dec 21, 2021 at 19:59

score 2 · Accepted Answer · 2021-12-21 19:53:10Z

2

You can use np.repeat twice, with axis=1 and axis=0:

out = a.repeat(2, axis=1).repeat(2, axis=0)

Output:

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

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How to enlarge a numpy array

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