Crate random_pick

Random Pick

Pick an element from a slice randomly by given weights.

Examples

extern crate random_pick;

enum Prize {
    Legendary,
    Rare,
    Enchanted,
    Common,
}

let prize_list = [Prize::Legendary, Prize::Rare, Prize::Enchanted, Prize::Common]; // available prizes

let slice = &prize_list;
let weights = [1, 5, 15, 30]; // a scale of chance of picking each kind of prize

let n = 1000000;
let mut counter = [0usize; 4];

for _ in 0..n {
    let picked_item = random_pick::pick_from_slice(slice, &weights).unwrap();

    match picked_item {
        Prize::Legendary=>{
            counter[0] += 1;
           }
        Prize::Rare=>{
            counter[1] += 1;
        }
        Prize::Enchanted=>{
            counter[2] += 1;
        }
        Prize::Common=>{
            counter[3] += 1;
        }
    }
}

println!("{}", counter[0]); // Should be close to 20000
println!("{}", counter[1]); // Should be close to 100000
println!("{}", counter[2]); // Should be close to 300000
println!("{}", counter[3]); // Should be close to 600000

The length of the slice is usually an integral multiple (larger than zero) of that of weights.

If you have multiple slices, you don't need to use extra space to concat them, just use the pick_from_multiple_slices function, instead of pick_from_slice.

Functions

gen_usize_with_weights	Get a usize value by given weights.
pick_from_multiple_slices	Pick an element from multiple slices randomly by given weights.
pick_from_slice	Pick an element from a slice randomly by given weights.