[Tutor] fast sampling with replacement

[Luke Paireepinart]

Can you explain what your function is doing and also post some test code to
profile it?

On Sat, Feb 20, 2010 at 10:22 AM, Andrew Fithian <afith13 at gmail.com> wrote:

> Hi tutor,
>
> I'm have a statistical bootstrapping script that is bottlenecking on a
> python function sample_with_replacement(). I wrote this function myself
> because I couldn't find a similar function in python's random library. This
> is the fastest version of the function I could come up with (I used
> cProfile.run() to time every version I wrote) but it's not fast enough, can
> you help me speed it up even more?
>
> import random
> def sample_with_replacement(list):
>     l = len(list) # the sample needs to be as long as list
>     r = xrange(l)
>     _random = random.random
>     return [list[int(_random()*l)] for i in r] # using
> list[int(_random()*l)] is faster than random.choice(list)
>
> FWIW, my bootstrapping script is spending roughly half of the run time in
> sample_with_replacement() much more than any other function or method.
> Thanks in advance for any advice you can give me.
>
> -Drew
>
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