[Scipy-tickets] [SciPy] #796: ndimage.shift destroys data from edges

SciPy Trac scipy-tickets@scipy....
Mon Oct 31 22:21:09 CDT 2011


#796: ndimage.shift destroys data from edges
---------------------------+------------------------------------------------
 Reporter:  0ion9          |       Owner:  somebody    
     Type:  defect         |      Status:  needs_review
 Priority:  normal         |   Milestone:  Unscheduled 
Component:  scipy.ndimage  |     Version:  devel       
 Keywords:                 |  
---------------------------+------------------------------------------------

Comment(by stefan):

 This patch is correct.  However, there is another missing piece of the
 puzzle.  If we return, for a size 4 array, 3.5 as the index, we should get
 a value interpolated between x[3] and x[4], which does not currently
 happen, since x is never extended to have 5 elements using the correct
 wrapping.

 See ni_interpolation.c line 249 in NI_SplineFilter1D, e.g.

 This again comes back to the way we define data points.  Ideally, the
 first and last data-points should be defined to have a distance of 1
 between them.

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/796#comment:6>
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