[Numpy-discussion] Non-contiguous array from newaxis indexing

Jens Jørgen Mortensen jensj@fysik.dtu...
Sat Aug 18 04:00:56 CDT 2007


I would like all these arrays to be contiguous:

>>> import numpy as npy
>>> npy.__version__
'1.0.4.dev3967'
>>> x = npy.arange(4)
>>> y = x[npy.newaxis, :]
>>> z = x.reshape((1, 4))
>>> for a in [x, y, z]:
...     print a.shape, a.strides, a.flags.contiguous
... 
(4,) (4,) True
(1, 4) (0, 4) False
(1, 4) (16, 4) True

But y is not contiguous according to y.flags.contiguous - why not and
why does y and z not have the same strides?

I found this comment just before the _IsContiguous function in
arrayobject.c:

/* 0-strided arrays are not contiguous (even if dimension == 1) */

Is this correct?

Jens Jørgen Mortensen




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