[Numpy-discussion] Bilateral filter

Zachary Pincus zachary.pincus@yale....
Sun Mar 1 15:53:30 CST 2009

Hi guys,

Dag, the cython person who seems to deal with the numpy stuff, had  
this to say:
> - cimport and import are different things; you need both.
> - The "dimensions" field is in Cython renamed "shape" to be closer  
> to the Python interface. This is done in Cython/Includes/numpy.pxd

After including both the 'cimport' and 'import' lines, and changing  
'dimensions' to 'shape', things work perfectly. And now the shoe is on  
the other foot -- I wonder why you guys were getting proper results  
with what Dag claims to be buggy code! Odd indeed.


On Mar 1, 2009, at 2:36 PM, Nadav Horesh wrote:

> 1. "dimensions" is a field in the C struct, that describes the array  
> object.
> 2. Is there a chance that the header file numpy/arrayobject.h  
> belongs to a
>   different numpy version that you run?
> I am not very experienced with cython (I suppose that Stefan has  
> some experience).
> As you said, probably the cython list is a  better place to look for  
> an answer. I would be happy to see how this issue resolved.
>  Nadav
> -----הודעה מקורית-----
> מאת: numpy-discussion-bounces@scipy.org בשם Zachary Pincus
> נשלח: א 01-מרץ-09 20:59
> אל: Discussion of Numerical Python
> נושא: Re: [Numpy-discussion] Bilateral filter
>>> Well, the latest cython doesn't help -- both errors still appear as
>>> below. (Also, the latest cython can't run the numpy tests either.)
>>> I'm
>>> befuddled.
>> That's pretty weird.  Did you remove the .so that was build as well  
>> as
>> any source files, before doing build_ext with the latest Cython?   
>> Also
>> good to make sure that the latest Cython is, in fact, the one being
>> used.
> Yeah... and I just tried that again, with the same results. I have no
> idea what could be going wrong. E.g. why would 'cimport numpy as np'
> not add np to the namespace on my machine whereas it does so on  
> yours...
> Also, I assume that constructs like:
>         cdef int i, dim = data.dimensions[0]
> are some special numpy-support syntax that's supposed to be added by
> the cimport numpy line? (Because numpy arrays don't expose a
> 'dimensions' attribute to python code...) It's like for some reason on
> my machine, cython isn't building its numpy support correctly. Which
> is understandable in the light of the fact that cython can't pass the
> numpy tests on my machine either. Odd indeed. Maybe I'll try on the
> cython list, since you guys seem to have demonstrated that the problem
> isn't in the bilateral code!
> Zach
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