On Wed, 24 Feb 2010 20:16:24 +0100, mk <mrk...@gmail.com> wrote:
> On 2010-02-24 20:01, Robert Kern wrote:
>> I will repeat my advice to just use random.SystemRandom.choice() instead
>> of trying to interpret the bytes from /dev/urandom directly.
>
> Out of curiosity:
>
> def gen_rand_string(length):
> prng = random.SystemRandom()
> chars = []
> for i in range(length):
> chars.append(prng.choice('abcdefghijklmnopqrstuvwxyz'))
> return ''.join(chars)
>
> if __name__ == "__main__":
> chardict = {}
> for i in range(10000):
> ## w = gen_rand_word(10)
> w = gen_rand_string(10)
> count_chars(chardict, w)
> counts = list(chardict.items())
> counts.sort(key = operator.itemgetter(1), reverse = True)
> for char, count in counts:
> print char, count
>
>
> s 3966
> d 3912
> g 3909
> h 3905
> a 3901
> u 3900
> q 3891
> m 3888
> k 3884
> b 3878
> x 3875
> v 3867
> w 3864
> y 3851
> l 3825
> z 3821
> c 3819
> e 3819
> r 3816
> n 3808
> o 3797
> f 3795
> t 3784
> p 3765
> j 3730
> i 3704
>
> Better, although still not perfect.
What would be perfect? Surely one shouldn't be happy if all the
tallies come out exactly equal: that would be a blatant indication
of something very nonrandom going on.
The tallies given above give a chi-squared value smack in the
middle of the range expected for random sampling of a uniform
distribution (p = 0.505). So the chi-squared metric of
goodness-of-fit to a unifom distribution says you're doing fine.
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