Resizing and stretching a NumPy array

Question

I am working in Python and I have a NumPy array like this:

[1,5,9] [2,7,3] [8,4,6] 

How do I stretch it to something like the following?

[1,1,5,5,9,9] [1,1,5,5,9,9] [2,2,7,7,3,3] [2,2,7,7,3,3] [8,8,4,4,6,6] [8,8,4,4,6,6] 

These are just some example arrays, I will actually be resizing several sizes of arrays, not just these.

I'm new at this, and I just can't seem to wrap my head around what I need to do.

Answer 1

@KennyTM's answer is very slick, and really works for your case but as an alternative that might offer a bit more flexibility for expanding arrays try np.repeat:

>>> a = np.array([[1, 5, 9],               [2, 7, 3],               [8, 4, 6]])  >>> np.repeat(a,2, axis=1) array([[1, 1, 5, 5, 9, 9],        [2, 2, 7, 7, 3, 3],        [8, 8, 4, 4, 6, 6]]) 

So, this accomplishes repeating along one axis, to get it along multiple axes (as you might want), simply nest the np.repeat calls:

>>> np.repeat(np.repeat(a,2, axis=0), 2, axis=1) array([[1, 1, 5, 5, 9, 9],        [1, 1, 5, 5, 9, 9],        [2, 2, 7, 7, 3, 3],        [2, 2, 7, 7, 3, 3],        [8, 8, 4, 4, 6, 6],        [8, 8, 4, 4, 6, 6]]) 

You can also vary the number of repeats for any initial row or column. For example, if you wanted two repeats of each row aside from the last row:

>>> np.repeat(a, [2,2,1], axis=0) array([[1, 5, 9],        [1, 5, 9],        [2, 7, 3],        [2, 7, 3],        [8, 4, 6]]) 

Here when the second argument is a list it specifies a row-wise (rows in this case because axis=0) repeats for each row.

Answer 2

>>> a = numpy.array([[1,5,9],[2,7,3],[8,4,6]]) >>> numpy.kron(a, [[1,1],[1,1]]) array([[1, 1, 5, 5, 9, 9],        [1, 1, 5, 5, 9, 9],        [2, 2, 7, 7, 3, 3],        [2, 2, 7, 7, 3, 3],        [8, 8, 4, 4, 6, 6],        [8, 8, 4, 4, 6, 6]])