[Numpy-discussion] Regression in mpl: AttributeError: incompatible shape for a non-contiguous array

Patrick Marsh patrickmarshwx@gmail....
Mon Oct 29 10:23:12 CDT 2012


I went ahead and filed a ticket (https://github.com/numpy/numpy/issues/2700)
for historical purposes…and so those on the MPL list can follow up.


PTM



---
Patrick Marsh
Ph.D. Candidate / Liaison to the HWT
School of Meteorology / University of Oklahoma
Cooperative Institute for Mesoscale Meteorological Studies
National Severe Storms Laboratory
http://www.patricktmarsh.com



On Mon, Oct 29, 2012 at 10:18 AM, Benjamin Root <ben.root@ou.edu> wrote:

>
>
> On Mon, Oct 29, 2012 at 11:04 AM, Patrick Marsh <patrickmarshwx@gmail.com>wrote:
>
>> Turns out it isn't the commit I thought it was. I'm currently going
>> through a git bisect to track down the actual commit that introduced this
>> bug. I'll post back when I've found it.
>>
>>
>>  PTM
>> ---
>> Patrick Marsh
>> Ph.D. Candidate / Liaison to the HWT
>> School of Meteorology / University of Oklahoma
>> Cooperative Institute for Mesoscale Meteorological Studies
>> National Severe Storms Laboratory
>> http://www.patricktmarsh.com
>>
>>
>>
>> On Mon, Oct 29, 2012 at 9:43 AM, Benjamin Root <ben.root@ou.edu> wrote:
>>
>>>
>>>
>>> On Mon, Oct 29, 2012 at 10:33 AM, Sebastian Berg <
>>> sebastian@sipsolutions.net> wrote:
>>>
>>>> Hey,
>>>>
>>>> On Mon, 2012-10-29 at 09:54 -0400, Benjamin Root wrote:
>>>> > This error started showing up in the test suite for mpl when using
>>>> > numpy master.
>>>> >
>>>> > AttributeError: incompatible shape for a non-contiguous array
>>>> >
>>>> > The tracebacks all point back to various code points where we are
>>>> > trying to set the shape of an array, e.g.,
>>>> >
>>>> > offsets.shape = (-1, 2)
>>>> >
>>>> Could you give a hint what these arrays history (how it was created) and
>>>> maybe .shape/.strides is? Sounds like the array is not contiguous when
>>>> it is expected to be, or the attribute setting itself fails in some
>>>> corner cases on master?
>>>>
>>>> Regards,
>>>>
>>>> Sebastian
>>>>
>>>>
>>> The original reporter of the bug dug into the commit list and suspects
>>> it was this one:
>>>
>>>
>>> https://github.com/numpy/numpy/commit/02ebf8b3e7674a6b8a06636feaa6c761fcdf4e2d
>>>
>>> However, it might be earlier than that (he is currently doing a clean
>>> rebuild to make sure).
>>>
>>> As for the history:
>>>
>>>             offsets = np.asanyarray(offsets)
>>>             offsets.shape = (-1, 2)             # Make it Nx2
>>>
>>> Where "offsets" comes in from (possibly) user-supplied data.  Nothing
>>> really all that special.  I will see if I can get stride information.
>>>
>>> Ben Root
>>>
>>>
> Further digging reveals that the code fails when the array is originally
> 1-D.  I had an array with shape (2,) and stride (8,).  The reshaping should
> result in a shape of (1, 2).
>
> Ben Root
>
>
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