[Numpy-discussion] [enhancement] sum_angle() and sum_polar()

Travis Oliphant travis at continuum.io
Mon May 28 13:58:26 EDT 2012

I didn't see anyone respond to this, but looking over his simple and elegant solution it seems like a useful addition to the 2-d functions available in NumPy as it works with any 2-d array (image or matrix) and does a transformation on the indices in order to organize the sum. 

It is not a general-purpose interpolating approach where the 2-d array is viewed as samples of an underlying continuous function. 

Are their other thoughts? 


On Mar 7, 2012, at 12:39 PM, Robert Jördens wrote:

> Hi everyone,
> I am proposing to add the the two following functions to
> numpy/lib/twodim_base.py:
> sum_angle() computes the sum of a 2-d array along an angled axis
> sum_polar() computes the sum of a 2-d array along radial lines or
> along azimuthal circles
> https://github.com/numpy/numpy/pull/230
> Comments?
> When I was looking for a solution to these problems of calculating
> special sums of 2-d arrays I could not find anything and it took me a
> while to figure out a (hopefully) useful and consistent algorithm.
> I can see how one would extend these to higher dimensions but that
> would preclude using bincount() to do the heavy lifting.
> Looking at some other functions, the doctests might need to be split
> into real examples and unittests.
> Best,
> -- 
> Robert Jordens.
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