[Numpy-discussion] is shuffle needlessly slow?

josef.pktd@gmai... josef.pktd@gmai...
Tue Jan 26 13:20:59 CST 2010


On Tue, Jan 26, 2010 at 2:00 PM, Alan G Isaac <aisaac@american.edu> wrote:
> Is this a fair test?
> I expected shuffle to be much faster
> (no array creation).
> Alan Isaac
>
>>>> import timeit
>>>>
>>>> setup = """
> ... import numpy as np
> ... prng = np.random.RandomState()
> ... N = 10**5
> ... indexes = np.arange(N)
> ... """
>>>>
>>>> print timeit.timeit('prng.shuffle(indexes)',setup, number=100)
> 5.69172311006
>>>> print timeit.timeit('indexes = prng.random_sample(N).argsort()',setup, number=100)
> 1.54648202495
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maybe because shuffle works with python objects and random_sample with floats

>>> a=['a','bb','cc','c','a'];np.random.shuffle(a);a
['c', 'a', 'bb', 'a', 'cc']

>>> np.random.random_sample(5)
array([ 0.02791159,  0.8451104 ,  0.51629232,  0.15428393,  0.39491844])

Josef
>>>


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