[NumPy-Tickets] [NumPy] #1396: Numpy product of zero-length array returns 1.0

NumPy Trac numpy-tickets@scipy....
Wed Feb 10 09:28:32 CST 2010


#1396: Numpy product of zero-length array returns 1.0
----------------------------------------+-----------------------------------
 Reporter:  xdylanm                     |       Owner:  somebody
     Type:  defect                      |      Status:  new     
 Priority:  normal                      |   Milestone:          
Component:  numpy.core                  |     Version:  1.3.0   
 Keywords:  product, prod, zero-length  |  
----------------------------------------+-----------------------------------
 {{{
 >>> numpy.prod([])
 1.0
 }}}


 or

 {{{
 >>> a = numpy.array([])
 >>> numpy.prod(a)
 1.0
 }}}


 This behaviour seems counterintuitive. Either an error should be raised
 (nothing to multiply) or it should return zero.

 Workaround: test the length of the array before passing to prod.

 numpy version 1.3.0

-- 
Ticket URL: <http://projects.scipy.org/numpy/ticket/1396>
NumPy <http://projects.scipy.org/numpy>
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