[SciPy-User] Convolving an ndarray by a function

Solbrig, Mr. Jeremy Jeremy.Solbrig@nrlmry.navy....
Wed Sep 26 15:25:53 CDT 2012


Hi all,

I have run into a situation where I need to calculate the standard deviation for each NxM box within an ndarray.  I am wondering if there is a function available that would allow me to convolve (may not be the correct word here) an ndarray by a function and return an array of the same size as the original array.  Something like this:

>>> foo = np.arange(10000).reshape([100,100])
>>> stddev_arr = foo.funcconvolve([3, 3], np.std) 
>>> stddev_arr.shape == foo.shape
True

Such that each point within stddev_arr is the standard deviation of a 3x3 box around each point in foo.  

I'm sure I could code this in a loop, but I expect that there is a better solution.

Thanks for your help,
Jeremy

Jeremy Solbrig
NRL Monterey
jeremy.solbrig@nrlmry.navy.mil
(831) 656-4885 



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