[SciPy-User] Bug in ndimage.map_coordinates with mode='wrap' ?

Kurt Smith kwmsmith@gmail....
Mon Mar 22 12:24:03 CDT 2010


On Mon, Mar 22, 2010 at 11:20 AM, Kurt Smith <kwmsmith@gmail.com> wrote:
> Hi,
>
> Testing the example code in ndimage.map_coordinate's docstring, I
> can't get things to work with mode='wrap'.  What am I doing wrong?
>
> In [31]: a
> Out[31]:
> array([[  0.,   1.,   2.],
>       [  3.,   4.,   5.],
>       [  6.,   7.,   8.],
>       [  9.,  10.,  11.]])
>
> In [32]: ndimage.map_coordinates(a, [range(5), [0]*5], order=1,
> mode='wrap')  # should be 0, 3, 6, 9, 0 -- right?
> Out[32]: array([ 0.,  3.,  6.,  9.,  3.])
>
> In [33]: ndimage.map_coordinates(a, [[0]*4, range(4)], order=1,
> mode='wrap')  # should be 0, 1, 2, 0 -- right?
> Out[33]: array([ 0.,  1.,  2.,  1.])
>
> Here's the output when extending the sampling range:
>
> In [36]: ndimage.map_coordinates(a, [range(10), [0]*10], order=1,
> mode='wrap')  # should be 0, 3, 6, 9, 0, 3, 6, 9, ...
> Out[36]: array([ 0.,  3.,  6.,  9.,  3.,  6.,  0.,  3.,  6.,  0.])
>
> In [37]: ndimage.map_coordinates(a, [[0]*8, range(8)], order=1, mode='wrap')
> Out[37]: array([ 0.,  1.,  2.,  1.,  0.,  1.,  0.,  1.])
>
>
> If it's a bug, where can I file a report, and what can I do to help
> fix it?  Looks like the wrapping code is in a compiled extension
> module -- I'll take a look.

I forgot to include:

In [39]: sp.version.version
Out[39]: '0.8.0.dev6120'


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