[SciPy-Dev] sum_angle() and sum_polar() functions

[Charles R Harris]

On Mon, May 21, 2012 at 2:06 AM, Robert Jördens <jordens at gmail.com> wrote:

> On Mon, May 21, 2012 at 1:16 AM, Ralf Gommers
> <ralf.gommers at googlemail.com> wrote:
> > Could you time the scikits-image version, it's not obvious from reading
> the
> > code that it will be very slow?
>
> In [47]: from scipy.misc.pilutil import radon as scipy_radon
> In [50]: from skimage.transform import radon as scikits_radon
>
> In [46]: a=np.random.randn(1000, 1000)
>
> In [53]: angle_sum(a, .1).shape
> Out[53]: (1100,)
>
> In [54]: scikits_radon(a, [.1]).shape
> Out[54]: (1415, 1)
>
> In [55]: scipy_radon(a, [.1]).shape
> Out[55]: (1000, 1)
>
> In [56]: %timeit angle_sum(a, .1)
> 10 loops, best of 3: 24.7 ms per loop
>
> In [57]: %timeit scikits_radon(a, [.1])
> 10 loops, best of 3: 136 ms per loop
>
> In [58]: %timeit scipy_radon(a, [.1])
> 10 loops, best of 3: 47.6 ms per loop
>
> In [59]: a.sum()
> Out[59]: -682.83728184031156
>
> In [60]: angle_sum(a, .1).sum()
> Out[60]: -682.83728184032327
>
> In [61]: scikits_radon(a, [.1]).sum()
> Out[61]: -682.83727334014043
>
> In [62]: scipy_radon(a, [.1]).sum()
> Out[62]: 124316062.0
>
> > My impression is that it would fit best in scikits-image. Perhaps ndimage
> > would be a reasonable place too. It's too specialized for numpy imho.
>
> angle_sum() at least can be applied beyond image processing in the
> analysis of coupling matrices or adjacency graphs. Both functions are
> simple and generic.
>
>
Looks like you need to sell this as a faster Radon or Hough, angle_sum is a
bit too generic ;)

Chuck
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