Python 3.12+randomfunction

random.binomialvariate

distributions

The number of successes in n Bernoulli trials with probability p; an int in [0, n] (3.12+).

Syntax

random.binomialvariate(n=1, p=0.5)

This is the only distribution function in random that hands back an int rather than a float. It collapses the loop sum(random.random() < p for _ in range(n)) into a single call, and does it much faster without scaling badly with n. It landed in 3.12 only, so older interpreters raise AttributeError and you write the sum by hand; a negative n or a p outside [0, 1] raises ValueError.

Examples

import random
print(0 <= random.binomialvariate(10, 0.5) <= 10)   # → True
print(random.binomialvariate() in (0, 1))   # → True
print(random.binomialvariate(10, 0.0), random.binomialvariate(10, 1.0))   # → 0 10
print(round(sum(random.binomialvariate(10, 0.5) for _ in range(10000)) / 10000))   # → 5
print(random.binomialvariate(10, 1.5))   # → ValueError

See also

Common errors

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