[Numpy-discussion] when did column_stack become C-contiguous?

[josef.pktd at gmail.com]

On Mon, Oct 19, 2015 at 1:27 AM, <josef.pktd at gmail.com> wrote:

>
>
> On Mon, Oct 19, 2015 at 1:10 AM, Stephan Hoyer <shoyer at gmail.com> wrote:
>
>> Looking at the git logs, column_stack appears to have been that way
>> (creating a new array with concatenate) since at least NumPy 0.9.2, way
>> back in January 2006:
>> https://github.com/numpy/numpy/blob/v0.9.2/numpy/lib/shape_base.py#L271
>>
>
> Then it must have been changed somewhere else between 1.6.1 amd 1.9.2rc1
>
> I have my notebook and my desktop with different numpy and python versions
> next to each other and I don't see a typo in my command.
>
> I assume python 2.7 versus python 3.4 doesn't make a difference.
>
> ------------------
>
> >>> np.column_stack((np.ones(10), np.ones(10))).flags
>   C_CONTIGUOUS : False
>   F_CONTIGUOUS : True
>   OWNDATA : False
>   WRITEABLE : True
>   ALIGNED : True
>   UPDATEIFCOPY : False
>
> >>> np.__version__
> '1.6.1'
> >>> import sys
> >>> sys.version
> '2.7.1 (r271:86832, Nov 27 2010, 18:30:46) [MSC v.1500 32 bit (Intel)]'
>
> ----------------
>
> >>> np.column_stack((np.ones(10), np.ones(10))).flags
>   C_CONTIGUOUS : True
>   F_CONTIGUOUS : False
>   OWNDATA : True
>   WRITEABLE : True
>   ALIGNED : True
>   UPDATEIFCOPY : False
>
> >>> np.__version__
> '1.9.2rc1'
> >>> import sys
> >>> sys.version
> '3.4.3 (v3.4.3:9b73f1c3e601, Feb 24 2015, 22:44:40) [MSC v.1600 64 bit
> (AMD64)]'
>
> ---------------------------
>
> comparing all flags, owndata also has changed, but I don't think that has
> any effect
>

qualification

It looks like in 1.9 it depends on the order of the 2-d arrays, which it
didn't do in 1.6

>>> np.column_stack((np.ones(10), np.ones((10, 2), order='F'))).flags
  C_CONTIGUOUS : False
  F_CONTIGUOUS : True
  OWNDATA : True
  WRITEABLE : True
  ALIGNED : True
  UPDATEIFCOPY : False


which means the default order looks more like "K" now, not "C", IIUC

Josef



>
> Josef
>
>
>>
>>
>> Stephan
>>
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>>
>
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