python - How to repeat elements of an array along two axes?

Question

I want to repeat elements of an array along axis 0 and axis 1 for M and N times respectively:

import numpy as np

a = np.arange(12).reshape(3, 4)
b = a.repeat(2, 0).repeat(2, 1)
print(b)

[[ 0  0  1  1  2  2  3  3]
 [ 0  0  1  1  2  2  3  3]
 [ 4  4  5  5  6  6  7  7]
 [ 4  4  5  5  6  6  7  7]
 [ 8  8  9  9 10 10 11 11]
 [ 8  8  9  9 10 10 11 11]]

This works, but I want to know are there better methods without create a temporary array.

Answer 1

You could use the kronecker product, see numpy.kron:

>>> a = np.arange(12).reshape(3,4)
>>> print np.kron(a, np.ones((2,2), dtype=a.dtype))
[[ 0  0  1  1  2  2  3  3]
 [ 0  0  1  1  2  2  3  3]
 [ 4  4  5  5  6  6  7  7]
 [ 4  4  5  5  6  6  7  7]
 [ 8  8  9  9 10 10 11 11]
 [ 8  8  9  9 10 10 11 11]]

Your original method is OK too, though!