[Numpy-discussion] Numpy array from ctypes pointer object?

Travis Oliphant oliphant.travis at ieee.org
Wed Jul 12 14:25:59 CDT 2006


Mark Heslep wrote:
> Travis Oliphant wrote:
>   
>> Mark Heslep wrote:
>>     
>>> I don't see a clean way to create a numpy array from a ctypes pointer 
>>> object. Is the __array_interface_ in ctypes the thing thats missing 
>>> needed to make this happen?  I've followed Albert's  Scipy cookbook 
>>> on ctypes here
>>>
>>> On the C side the PyArray_SimpleNewFromData( ..dimensions, ...data 
>>> ptr) C API does the job nicely.  Is there a ctypes paradigm for 
>>> SimpleNew...?
>>>   
>>>       
>> Can you somehow call this function using ctypes?
>>
>> -Travis
>>     
> That might work, though indirectly.  As I think I understand from ctypes 
> docs:  Ctypes uses functions exposed in a  shared library, macros 
> existing only a header are not available.  If its PyArray... is a macro 
> then I a) need to compile and make a little library directly from 
> arrayobject.h or b) need to use the root function upon which the macro 
> is based, PyArrayNew?
>
>   
This is more complicated because all the C-API functions are actually 
just pointers stored in _ARRAY_API of multiarray.    So, something would 
have to be built to interpret the C-pointers in that C-Object.  I'm not 
sure that is possible.

-Travis





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