[SciPy-dev] Indexing array performance

Francesc Altet faltet at carabos.com
Sat Dec 31 06:15:31 CST 2005


Hi,

I'm doing some timings on array indexing feature. It's quite shocking
to me that, provided empty() and arange() are faster in scipy_core
than its counterparts in numarray:

In [110]: t1 = timeit.Timer('a=empty(shape=10000);a=arange(10000)','from 
scipy.base import empty, arange')

In [111]: t1.repeat(3,10000)
Out[111]: [0.74018502235412598, 0.76141095161437988, 0.71947312355041504]

In [112]: t2 = timeit.Timer('a=array(None,shape=10000);a=arange(10000)','from 
numarray import array, arange')

In [113]: t2.repeat(3,10000)
Out[113]: [2.3724348545074463, 2.4109888076782227, 2.3820669651031494]

however, the next code seems to be slower in scipy_core:

In [114]: t3 = timeit.Timer('a=empty(shape=10000);a[arange(10000)]','from 
scipy.base import empty, arange')

In [115]: t3.repeat(3,1000)
Out[115]: [3.5126161575317383, 3.5309510231018066, 3.5558919906616211]

In [116]: t4 = timeit.Timer('a=array(None,shape=10000);a[arange(10000)]','from 
numarray import array, arange')

In [117]: t4.repeat(3,1000)
Out[117]: [2.0824751853942871, 2.1258058547973633, 2.0946059226989746]

It seems like if the index array feature can be further optimized in
scipy_core.

-- 
>0,0<   Francesc Altet     http://www.carabos.com/
V   V   Cárabos Coop. V.   Enjoy Data
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