random.gauss: range

Gregory Ewing greg.ewing at canterbury.ac.nz
Sun Feb 28 05:27:11 CET 2010


Steven D'Aprano wrote:
> def pinned_gaussian(a, b, mu, sigma):
>     """Return a Gaussian random number pinned to [a, b]."""
>     return min(b, max(a, random.gauss(mu, sigma)))
> 
> def truncated_gauss(a, b, mu, sigma):
>     """Return a random number from a truncated Gaussian distribution."""
>     while 1:
>         x = random.gauss(mu, sigma)
>         if a <= x <= b:
>             return x

If it doesn't have to be strictly gaussian, another way is to
approximate it by adding some number of uniformly distributed
samples together. If you have n uniform samples ranging from
0 to a, the sum will be in the range 0 to n*a and the mean
will be n*a/2. The greater the value of n, the closer the
distribution will be to normal.

-- 
Greg



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