Attach two 3d numpy arrays in Python

Question

I was wondering how I can attach two 3d numpy arrays in python?

For example, I have one with shape (81,81,61) and I would like to get instead a (81,81,122) shape array by attaching the original array to itself in the z direction.

this question was first so I don't want to flag it as a duplicate, but there's another identical question with more votes and a slightly better answer (also from Alex Riley): stackoverflow.com/questions/34357617/… — craq
– craq, Commented Sep 5, 2019 at 0:03

Alex Riley · Accepted Answer · 2015-02-09 16:55:41Z

10

One way is to use np.dstack which concatenates the arrays along the third axis (d is for depth).

For example:

>>> a = np.arange(8).reshape(2,2,2)
>>> np.dstack((a, a))
array([[[0, 1, 0, 1],
        [2, 3, 2, 3]],

       [[4, 5, 4, 5],
        [6, 7, 6, 7]]])

>>> np.dstack((a, a)).shape
(2, 2, 4)

You could also use np.concatenate((a, a), axis=2).

edited Feb 9, 2015 at 16:55

answered Feb 9, 2015 at 16:48

Alex Riley

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