roulette-wheel-rs

轮盘赌的简单实现（用于遗传算法中的选择）

lib.rs:

轮盘赌原理的简单实现，RouletteWheel<T>. https://wikipedia.org/wiki/Fitness_proportionate_selection

示例用法

use roulette_wheel::RouletteWheel;

fn evaluate(individual: &i32) -> f32 { *individual as f32 } // mmm...!

let population: Vec<_> = (1..10).into_iter().collect();
let fitnesses: Vec<_> = population.iter().map(|ind| evaluate(ind)).collect();

let rw: RouletteWheel<_> = fitnesses.into_iter().zip(population).collect();

// let's collect the individuals in the order in which the roulette wheel gives them
let individuals: Vec<_> = rw.into_iter().map(|(_, ind)| ind).collect();
// rw.select_iter() will not consume the roulette wheel
// while rw.into_iter() will !

fn crossover(mother: &i32, _father: &i32) -> i32 { mother.clone() } // unimplemented!()

// now merge each individual by couples
let new_population: Vec<_> = individuals.chunks(2)
                                 .filter(|couple| couple.len() == 2)
                                 .map(|couple| {
                                      let (mother, father) = (couple[0], couple[1]);
                                      crossover(&mother, &father)
                                      // note: for this example we return only one individual,
                                      //       the population will shrink
                                      //       .flat_map() can resolve this issue
                                  }).collect();