[Numpy-discussion] dedicated function for resize with averaging or rebin 2d arrays?

Andrea Zonca zonca@deepspace.ucsb....
Mon Nov 14 16:02:37 CST 2011


thanks,

On Mon, Nov 14, 2011 at 09:24, Chris.Barker <Chris.Barker@noaa.gov> wrote:
> On 11/11/11 8:28 PM, Craig Yoshioka wrote:
>> I once wrote a generic n-dimensional binning routine in C that I
>> could find if anyone is interested in integrating it into numpy... it
>> didn't do size increases though... and I think I implemented it so
>> that binning by a non-divisible factor trimmed the extras.  It was
>> very-very fast though.
>
> And I've got one written in Cython. I'd been thinking of contributing it
> to ndimage, but never got around to it -- but I'd be glad to share. Let
> me know if you want it.

Chris, I think this would be useful, can you make it available publicly?

>>> I think the usefulness of the rebin function is to be simple and fast,
>>> and the best would be to implement it in the core numpy, as a simple
>>> method for smoothing and reshaping,
>
> Does it have common use=-cases outside image processing? If not, then
> no, it shouldn't be in numpy.

actually the most common use is outside of image processing, we typically
use it when we have data that come from a detector scanning the sky in
circles, so you have a row for each scan.
It is nice to apply a quick and dirt decimation of the dataset by binning it.
It is such a simple function that would make more sense, to me, to
have in numpy.
In image processing I imagine you typically want to apply window functions,
so for that ndimage is more appropriate.

cheers,
andrea


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