[Python-Dev] PEP: Extending the buffer protocol to share array information.

["Martin v. Löwis"]

Travis E. Oliphant schrieb:
>     Several extensions to Python utilize the buffer protocol to share
>     the location of a data-buffer that is really an N-dimensional
>     array.  However, there is no standard way to exchange the
>     additional N-dimensional array information so that the data-buffer
>     is interpreted correctly.  The NumPy project introduced an array
>     interface (http://numpy.scipy.org/array_interface.shtml) through a
>     set of attributes on the object itself.  While this approach
>     works, it requires attribute lookups which can be expensive when
>     sharing many small arrays.  

Can you please give examples for real-world applications of this
interface, preferably examples involving multiple
independently-developed libraries?
("this" being the current interface in NumPy - I understand that
 the PEP's interface isn't implemented, yet)

Paul Moore (IIRC) gave the example of equalising the green values
and maximizing the red values in a PIL image by passing it to NumPy:
Is that a realistic (even though not-yet real-world) example? If
so, what algorithms of NumPy would I use to perform this image
manipulation (and why would I use NumPy for it if I could just
write a for loop that does that in pure Python, given PIL's
getpixel/setdata)?

Regards,
Martin