python - How to make a 2d numpy array a 3d array?

Question

I have a 2d array with shape (x, y) which I want to convert to a 3d array with shape (x, y, 1). Is there a nice Pythonic way to do this?

Answer 1

In addition to the other answers, you can also use slicing with numpy.newaxis:

>>> from numpy import zeros, newaxis
>>> a = zeros((6, 8))
>>> a.shape
(6, 8)
>>> b = a[:, :, newaxis]
>>> b.shape
(6, 8, 1)

Or even this (which will work with an arbitrary number of dimensions):

>>> b = a[..., newaxis]
>>> b.shape
(6, 8, 1)