Struct Choose

A distribution to uniformly sample elements of a slice

Like IndexedRandom::choose, this uniformly samples elements of a slice without modification of the slice (so called "sampling with replacement"). This distribution object may be a little faster for repeated sampling (but slower for small numbers of samples).

Examples

Since this is a distribution, Rng::sample_iter and Distribution::sample_iter may be used, for example:

use rand::distr::{Distribution, slice::Choose};

let vowels = ['a', 'e', 'i', 'o', 'u'];
let vowels_dist = Choose::new(&vowels).unwrap();

// build a string of 10 vowels
let vowel_string: String = vowels_dist
    .sample_iter(&mut rand::rng())
    .take(10)
    .collect();

println!("{}", vowel_string);
assert_eq!(vowel_string.len(), 10);
assert!(vowel_string.chars().all(|c| vowels.contains(&c)));

For a single sample, IndexedRandom::choose may be preferred:

use rand::seq::IndexedRandom;

let vowels = ['a', 'e', 'i', 'o', 'u'];
let mut rng = rand::rng();

println!("{}", vowels.choose(&mut rng).unwrap());