[NumPy-Tickets] [NumPy] #1386: 100 times poorer performance indexing scalar record array

NumPy Trac numpy-tickets@scipy....
Sun Jan 31 15:37:30 CST 2010


#1386: 100 times poorer performance indexing scalar record array
---------------------------+------------------------------------------------
 Reporter:  oscar.bristol  |       Owner:  somebody
     Type:  defect         |      Status:  new     
 Priority:  normal         |   Milestone:          
Component:  numpy.core     |     Version:          
 Keywords:                 |  
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Comment(by oscar.bristol):

 (Second attempt)
 Assigning to a field in a scalar record array like this:
 {{{
 B['a'][:] = A['a'][:]
 }}}
 takes around 50 times as long as assigning like this:
 {{{
 B['a'][:] = A['a']
 }}}
 and 100 times as long as assigning to a size 1 record array. I've attached
 a script (test.py) that compares scalars and size 1 arrays and the two
 different methods of indexing above. On my machine, the results are:

 {{{
 $ python test.py 100000
 array,  B['a'][:] = A['a'] 0.25 seconds
 array,  B['a']    = A['a'] 0.213 seconds
 scalar, B['a'][:] = A['a'] 0.395 seconds
 scalar, B['a']    = A['a'] 22.0 seconds
 }}}

-- 
Ticket URL: <http://projects.scipy.org/numpy/ticket/1386#comment:1>
NumPy <http://projects.scipy.org/numpy>
My example project


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