Tartifola wrote:
> I have a list with probabilities as elements
>
> [p1,p2,p3]
>
> with of course p1+p2+p3=1. I'd like to draw a
> random element from this list, based on the probabilities contained in
> the list itself, and return its index.
>
> Any help on the best way to do that?
import random
import bisect
def draw(probabilities):
sigma = 0.0
ps = []
for p in probabilities:
sigma += p
ps.append(sigma)
_bisect = bisect.bisect
_random = random.random
while 1:
yield _bisect(ps, _random())
if __name__ == "__main__":
from itertools import islice
histo = [0]*4
for i in islice(draw([0.2, 0.3, 0.5]), 100000):
histo[i] += 1
print histo
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