Re: [matplotlib-devel] Small change to speed up imshow()

[John H. <jdh...@ac...>]

>>>>> "Zelakiewicz," == Zelakiewicz, Scott (Research) <zel...@cr...> writes:

    Scott> I routinely plot fairly large datasets (~4million
    Scott> points) using imshow but on my machine this takes
    Scott> about 11 secs to complete.  I went through the code
    Scott> and made a couple of minor changes where the image
    Scott> data would get clipped by vmax and vmin only if the
    Scott> user supplied a vmax or vmin.  The clipping is
    Scott> unnecessary if the user does not supply these values
    Scott> since vmax and vmin default to the max and min in
    Scott> the image.  I also replaced two successive
    Scott> where(...) calls with a single clip(...) call and
    Scott> that seems to have helped a tiny bit as well.  This
    Scott> change has been tested on 0.80 compiled with
    Scott> Numeric, though I can't envision how this would
    Scott> break anything.  The profiler tells me that my plot
    Scott> time has decreased from 11.8 sec to 7.2 sec.  Hope
    Scott> this helps.

Thanks Scott -- this simple optimization should help a lot with common
use cases.  I've applied it in my local tree (hasn't made CVS yet
because there are other more significant changes I'm working on that I
can't commit yet).

Thanks!
JDH