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MyASPN >> Mail Archive >> numpy-discussion
numpy-discussion
Re: [Numpy-discussion] Is sum() slow?
by Sasha other posts by this author
Mar 8 2006 7:33PM messages near this date
Re: [Numpy-discussion] Is sum() slow? | Re: [Numpy-discussion] Is sum() slow?
On 3/7/06, Travis Oliphant <oliphant@[...].edu>  wrote:
>  ...
>  I'm a little surprised that Numeric is so much faster for this case as
>  you show later.
> 
Here is another puzzle:

>  python -m timeit -s "from Numeric import zeros,sum; x = zeros((2,500),'f')" "sum(x,0)"
100000 loops, best of 3: 6.05 usec per loop
>  python -m timeit -s "from Numeric import zeros,sum; x = zeros((500,2),'f')" "sum(x,1)"
10000 loops, best of 3: 26.8 usec per loop

>  python -m timeit -s "from numpy import zeros; x = zeros((2,500),'f')" "x.sum(0)"
10000 loops, best of 3: 22.8 usec per loop
>  python -m timeit -s "from numpy import zeros; x = zeros((500,2),'f')" "x.sum(1)"
10000 loops, best of 3: 23.6 usec per loop

Numpy and Numeric perform very similarly when reducing along the second axis.

>  If anyone can figure out how to make the NOBUFFER secion in
>  GenericReduce faster in ufuncobject.c it will be greatly welcomed.

Here is my $.02:
<http://projects.scipy.org/scipy/numpy/wiki/PossibleOptimizationAreas/ReduceDiscussion> 

BTW, I've tried to take loop-> ... redirections out of the loop: no
effect with gcc -O3 .


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Thread:
Mads Ipsen
Travis Oliphant
Sasha
Alexander Belopolsky

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