weighted-random

Install

You know the drill:

npm install @ldegen/weighed-random

Usage

It works like this: You have a (finite) distribution, i.e. an array containing 'weights'. Use this to create a WeigtedRandom function that will return indices into this array.

var WeightedRandom = require('@ldegen/weighted-random');

// don't worry, weights will be normalized so that the sum up to 1.0
var wr = WeightedRandom([0 ,12, 6, 3]);

// choice will be 
// 0  never, 
// 1  with probability 4/7, 
// 2  with probability 2/7 or 
// 3  with probability 1/7 

var choice = wr(); 

By default, WeightedRandom uses Math.random(), but you can use any parameter-less function that returns float between 0.0 (inclusive) and 1.0 (exclusive). Just pass it as second argument like this:

var wr = WeightedRandom([0 ,12, 6, Math.PI/2], myCustomMathRandomReplacement);