RosettaCodeData/Task/Unbias-a-random-generator/Python/unbias-a-random-generator.py

29 lines
957 B
Python

from __future__ import print_function
import random
def randN(N):
" 1,0 random generator factory with 1 appearing 1/N'th of the time"
return lambda: random.randrange(N) == 0
def unbiased(biased):
'uses a biased() generator of 1 or 0, to create an unbiased one'
this, that = biased(), biased()
while this == that: # Loop until 10 or 01
this, that = biased(), biased()
return this # return the first
if __name__ == '__main__':
from collections import namedtuple
Stats = namedtuple('Stats', 'count1 count0 percent')
for N in range(3, 7):
biased = randN(N)
v = [biased() for x in range(1000000)]
v1, v0 = v.count(1), v.count(0)
print ( "Biased(%i) = %r" % (N, Stats(v1, v0, 100. * v1/(v1 + v0))) )
v = [unbiased(biased) for x in range(1000000)]
v1, v0 = v.count(1), v.count(0)
print ( " Unbiased = %r" % (Stats(v1, v0, 100. * v1/(v1 + v0)), ) )