Weighted random choice

Python 带权重的随机选择。via

import random

def windex(lst):
    '''an attempt to make a random.choose() function that makes weighted choices
    accepts a list of tuples with the item and probability as a pair
    like: >>> x = [('one', 0.25), ('two', 0.25), ('three', 0.5)]
    >>> y=windex(x)'''

    n = random.uniform(0, 1)
    for item, weight in lst:
        if n < weight:
            break
        n = n - weight
    return item