[Numpy-discussion] Profiling numpy ? (parts written in C)
david at ar.media.kyoto-u.ac.jp
Tue Dec 19 20:41:02 CST 2006
Charles R Harris wrote:
> My guess is that the real bottleneck is in calling so many times
> memmove (once per element in the array). Perhaps the algorithm can be
> changed to do a block copy at the beginning and then modify only the
> places on which the clip should act (kind of the same that you have
> made in Python, but at C level).
> IIRC, doing a simple type specific assignment is faster than either
> memmov or memcpy. If speed is really of the essence it would probably
> be worth writing a type specific version of clip. A special function
> combining clip with RGB conversion might do even better.
At the end, in the original context (speeding the drawing of
spectrogram), this is the problem. Even if multiple backend/toolkits
have obviously an impact in performances, I really don't see why a numpy
function to convert an array to a RGB representation should be 10-20
times slower than matlab on the same machine.
I will take into account all those helpful messages, and hopefully come
with something for the end of the week :),
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