Index of numpy array is None

Asked Aug 15 '17 at 20:51

Active Aug 15 '17 at 20:53

Viewed 36 times

For example, a matrix X

>>> X
array([[ 0,  1,  2,  3,  4],
       [ 5, -1,  7,  8,  9]])

what is the meaning of >>> X[None,:]

array([[[ 0,  1,  2,  3,  4],
        [ 5, -1,  7,  8,  9]]])

So, it changes the dimension of the matrix respect to the None axis? Am I right? Thanks for any help.

edited Aug 15 '17 at 20:53

asked Aug 15 '17 at 20:51

Mozzie

That's not a list. That's a NumPy array. – user2357112 Aug 15 '17 at 20:53
sorry for my mistake. It is a numpy array. – Mozzie Aug 15 '17 at 20:54
It adds a dimension. `X` is 2d (2,5); `X[None, :, :]` is 3d (1,2,5). – hpaulj Aug 16 '17 at 01:03

0 Answers0