Pure Python random laws

poisson.py

import math
import random

def poisson(l, rng=random):
    """From https://www.johndcook.com/blog/2010/06/14/generating-poisson-random-values/"""
    
    L = math.exp(-l)
    k = 0
    p = 1
    
    while p > L:
        k += 1
        p *= rng.uniform(0, 1)
        
    return k - 1

poisson(1)