[Numpy-discussion] numpy array to C API

Søren sd at syntonetic.com
Thu Mar 21 12:17:15 EDT 2013

Thanks Valentin

Your article fell in dry spot when a newbie in C/Python interfacing.
Python-C-API fits perfectly with my current use-case.

I got currious about the Ctypes approach as well as "Gaël Varoquaux’s 
blog post about avoiding data copies", but the link in the article 
didn't seem to work. (Under "Further Reading and References")


On 21/03/2013 09:41, Valentin Haenel wrote:
> Dear Søren,
> if you are new to interfacing python/numpy with C/C++, you may want to
> check out:
> http://scipy-lectures.github.com/advanced/interfacing_with_c/interfacing_with_c.html
> Disclaimer: I am the author of this chapter, so this response is a bit
> of a shameless plug :D
> Hope it helps.
> V-
> * Søren <sd at syntonetic.com> [2013-03-21]:
>> Thanks Robert, for making that clear.
>> I got a deprecated warning the second I added
>> #include <numpy/arrayobject.h>
>> and I got scared off too fast in my exploring phase.
>> Cheers
>> Søren
>> On 20/03/2013 17:03, Robert Kern wrote:
>>> On Wed, Mar 20, 2013 at 1:59 PM, Søren <sd at syntonetic.com> wrote:
>>>> Greetings
>>>> I'm extending our existing C/C++ software with Python/Numpy in order to do extra number crunching.
>>>> It already works like a charm calling python with the C API <Python.h>.
>>>> But what is the proper way of passing double arrays returned from Python/Numpy routines back to C?
>>>> I came across PyArray but I can see in the compiler warnings, it is deprecated and I don't wanna start from scratch on legacy facilities.
>>> What is this `PyArray` that you are referring to? There is nothing
>>> named just `PyArray` to my knowledge. Do you mean direct access to the
>>> `data` member of the PyArrayObject struct? Yes, that is deprecated.
>>> Use the PyArray_DATA() macro to get a `void*` pointer to the start of
>>> the data.
>>> http://docs.scipy.org/doc/numpy/reference/c-api.array.html#PyArray_DATA
>>> --
>>> Robert Kern
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