numpy concatenate multiple arrays arrays

Question

I have many numpy arrays of shape (Ni,227,227,3), where Ni of each array is different.

I want to join them and make array of shape (N1+N2+..+Nk,227,227,3) where k is the number of arrays.

I tried numpy.concatenate and numpy.append but they ask for same dimension in axis 0. I am also confused on what is axis 1 and axis 2 in my arrays.

np.concatenate(alist, axis=0) should work. Don't do this in a loop - collect a list of all the array, and do one concatenate. Forget about np.append. — hpaulj
– hpaulj, Commented Jun 25, 2018 at 6:10
np.concatenate([a,b,c,d],axis=0) gives me ValueError: all the input arrays must have same number of dimension, ----- and the shapes are (1500, 227, 227, 3) (1500, 227, 227, 3) (0,) (1380, 227, 227, 3) — Shreyas Pimpalgaonkar
– Shreyas Pimpalgaonkar, Commented Jun 25, 2018 at 6:25
The (0,) does not have the same number of dimensions as the others. — hpaulj
– hpaulj, Commented Jun 25, 2018 at 6:30

Shreyas Pimpalgaonkar · Accepted Answer · 2018-07-05 13:04:54Z

0

So, the main problem here was with the one of the arrays of shape (0,) instead of (0,227,227,3).

np.concatenate(alist,axis=0) works.

answered Jul 5, 2018 at 13:04

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