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) 

Answer 2

numpy.reshape(array, array.shape + (1,))