[NumPy-Tickets] [NumPy] #1429: inconsistent behavior of argmin/argmax with nan

NumPy Trac numpy-tickets@scipy....
Mon Mar 15 17:23:34 CDT 2010

#1429: inconsistent behavior of argmin/argmax with nan
 Reporter:  jgregoire          |       Owner:  somebody
     Type:  defect             |      Status:  new     
 Priority:  normal             |   Milestone:          
Component:  Other              |     Version:  1.3.0   
 Keywords:  argmin argmax nan  |  
 This is related to Ticket #1035 but I believe is an unreported issue.
 When the array contains nan, argmin and argmax ignore the nan. The problem
 is that if the zeroth element of the array is nan then argmin and argmax
 return 0. Having the behavior of a function depend on the value of the
 zeroth element is very undesirable.

 In [1]: import numpy as np

 In [2]: a=np.array([1., 2., 0., np.nan])

 In [3]: print np.argmin(a), np.argmax(a)
 ------> print(np.argmin(a), np.argmax(a))
 (2, 1)

 In [4]: print np.argmin(a[::-1]), np.argmax(a[::-1])
 ------> print(np.argmin(a[::-1]), np.argmax(a[::-1]))
 (0, 0)

Ticket URL: <http://projects.scipy.org/numpy/ticket/1429>
NumPy <http://projects.scipy.org/numpy>
My example project

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