A Rust implementation of roulette wheel selection using the Alias Method. This can be used to simulate a loaded die and similar situations.

Initialization takes O(n) time; choosing a random element takes O(1) time. This is far faster than naive algorithms (the most common of which is commonly known as 'roulette wheel selection'). For an in-depth explanation of the algorithm, see http://www.keithschwarz.com/darts-dice-coins/.

This code was translated from http://www.keithschwarz.com/interesting/code/?dir=alias-method.

Example

let mut rng = rand::thread_rng();
let roulette = Roulette::new(vec![
    ('a', 1.0), ('b', 1.0), ('c', 0.5), ('d', 0.0)]);
for _ in range(0, 10) {
    let rand = roulette.next(&mut rng);
    println!("{}", rand);
}