[NumPy-Tickets] [NumPy] #1922: Indexing arrays with arrays having redundant entries

NumPy Trac numpy-tickets@scipy....
Tue Aug 2 09:56:57 CDT 2011


#1922: Indexing arrays with arrays having redundant entries
----------------------------+-----------------------------------------------
 Reporter:  gfabbian        |       Owner:  somebody   
     Type:  defect          |      Status:  new        
 Priority:  normal          |   Milestone:  Unscheduled
Component:  numpy.numarray  |     Version:  1.6.0      
 Keywords:  array indexing  |  
----------------------------+-----------------------------------------------
 I'm experiencing a problem with array indexing. Suppose you have an array
 a and another array b you want to use to use as index for a in order to
 assign some values to the position pointed by b elements.


 {{{
 >>>a=numpy.zeros(5)

 >>> print a

 >>>[ 0.  0.  0.  0.  0.]
 }}}


 Now I would like to increase the second element twice using this technique

 {{{
 >>>b=numpy.array([1,1])

 >>>a[b]+=1.

 >>> print a

 >>>[ 0.  1.  0.  0.  0.]

 }}}

 while I expected to have

 {{{
 >>>[ 0.  2.  0.  0.  0.]
 }}}


 There are no problems if the array b has no redundancies (all values of
 its elements are different).
 Is it a bug or I'm missing something?


 Thanks in advance

-- 
Ticket URL: <http://projects.scipy.org/numpy/ticket/1922>
NumPy <http://projects.scipy.org/numpy>
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