Check if numpy array is contiguous?

Question

How can I find out if a n-dimensional numpy array Arr is contiguous in C-style or Fortran-style?

score 19 · Accepted Answer · edited Feb 21 '19 at 08:19

19

The numpy documentation states that it is possible to check whether an array is C-contiguous or Fortran-contiguous via the attribute flags:

Arr.flags['C_CONTIGUOUS']
Arr.flags['F_CONTIGUOUS']

These attributes return a boolean indicating which of the two cases is true.

edited Feb 21 '19 at 08:19

ractiv

answered Jul 12 '18 at 11:12

Ethunxxx

1

Excepts it is not a function, it is actually an attribute of the `numpy.ndarray` object, as your reported syntax (which is correct) suggests. – norok2 Jul 12 '18 at 11:38
@norok2, you are right! I edited the answer. Thanks! – Ethunxxx Jul 12 '18 at 11:49
3

And with some axis swapping it possible that neither will be True. And both are True for a 1d array – hpaulj Jul 12 '18 at 15:11

score 10 · Answer 2 · answered Feb 12 '20 at 21:11

10

You can also try the ndarray.data.contiguous member. E.g. (on my machine):

arr = np.arange(6).reshape(2, 3)

print(arr.data.contiguous)  # True
print(arr.data.c_contiguous)  # True
print(arr.data.f_contiguous)  # False

(I can't find any information re: which numpy versions support this, even on their docs. Any leads welcome in the comments!)

answered Feb 12 '20 at 21:11

CrepeGoat

Note: this will not work with `datetime64` arrays; you get `ValueError: cannot include dtype 'M' in a buffer` – flexatone Sep 27 '22 at 15:49

2 Answers2