Weighted choice short and simple [duplicate]

Question

If I have a collection of items in a list. I want to choose from that list according to another list of weights.

For example my collection is ['one', 'two', 'three'] and the weights are [0.2, 0.3, 0.5], the I would expect the method to give me 'three' in about half of all draws.

What is the easiest way to do so ?

Answer 1

Since numpy version 1.7 you can use numpy.random.choice():

elements = ['one', 'two', 'three']  weights = [0.2, 0.3, 0.5]  from numpy.random import choice print(choice(elements, p=weights)) 

Answer 2

Since Python 3.6, you can do weighted random choice (with replacement) using random.choices.

random.choices(population, weights=None, *, cum_weights=None, k=1)

Example usage:

import random random.choices(['one', 'two', 'three'], [0.2, 0.3, 0.5], k=10) # ['three', 'two', 'three', 'three', 'three', #  'three', 'three', 'two', 'two', 'one']