[NumPy-Tickets] [NumPy] #2149: interp(nan, ...) should yield nan

NumPy Trac numpy-tickets@scipy....
Thu May 31 10:26:37 CDT 2012


#2149: interp(nan, ...) should yield nan
------------------------+---------------------------------------------------
 Reporter:  ehiggs      |       Owner:  somebody   
     Type:  defect      |      Status:  new        
 Priority:  normal      |   Milestone:  Unscheduled
Component:  Other       |     Version:  1.6.1      
 Keywords:  nan interp  |  
------------------------+---------------------------------------------------
 Passing nan to the first argument of interp appears to return the first
 element of fp. This isn't a meaningful value and can silently corrupt data
 since nan went in and undetectable garbage came out.

 {{{
 >>> import numpy as np
 >>> np.interp(1, [-10, 10], [-2, 2])
 0.20000000000000018
 >>> np.interp(np.nan, [-10, 10], [-2, 2])
 -2.0
 >>> np.interp([np.nan, 1], [-10, 10], [-2, 2])
 array([-2. ,  0.2])
 }}}

 This -2.0 is not a meaningful answer. The interpolation of a nan value
 should probably also be nan.

 Thanks

-- 
Ticket URL: <http://projects.scipy.org/numpy/ticket/2149>
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