PMX - Partially Mapped Crossover

pmx.js

function x(s, t) {
  let _map1 = {};
  let _map2 = {};

  const x1 = Math.floor(Math.random() * (s.length - 1));
  const x2 = x1 + Math.floor(Math.random() * (s.length - x1));

  let offspring = [Array.from(s), Array.from(t)];

  for (let i = x1; i < x2; i++) {
    offspring[0][i] = t[i];
    _map1[t[i]] = s[i];

    offspring[1][i] = s[i];
    _map2[s[i]] = t[i];
  }

  for (let i = 0; i < x1; i++) {
    while (offspring[0][i] in _map1) {
      offspring[0][i] = _map1[offspring[0][i]];
    }
    while (offspring[1][i] in _map2) {
      offspring[1][i] = _map2[offspring[1][i]];
    }
  }

  for (let i = x2; i < s.length; i++) {
    while (offspring[0][i] in _map1) {
      offspring[0][i] = _map1[offspring[0][i]];
    }
    while (offspring[1][i] in _map2) {
      offspring[1][i] = _map2[offspring[1][i]];
    }
  }
  return offspring;
}

function PMXCrossover(pop) {
  const p = pop.members;
  const rounds = p.length % 2 ? p.length - 1 : p.length;
  for (let i = 1; i < rounds; i += 2) {
    const s = p[i].genome;
    const t = p[i - 1].genome;
    x(s, t).forEach((offspring) => {
      if (new Set(offspring).size != _cities.length) {
        console.log(offspring);
        throw new Error("nope");
      }
      pop.members.push(new Citizen(offspring));
    });

  }
}

pmx.rs

fn crossover(&self, other: &TspTour) -> TspTour {
    // PMX crossover
    let s = &self.tour;
    let t = &other.tour;

    let mut rng = self.rng_cell.borrow_mut();
    let x1 = rng.gen_range(0, s.len() - 1);
    let x2 = rng.gen_range(x1, s.len());

    let mut offspring = vec![0; s.len()];
    let mut mapping: Vec<Option<usize>> = vec![None; s.len()];

    for i in x1..x2 {
        offspring[i] = t[i];
        mapping[t[i]] = Some(s[i]);
    }

    for i in 0..x1 {
        let mut o = mapping[s[i]];
        let mut last = None;
        while o.is_some() {
            last = o;
            o = mapping[o.unwrap()];
        }
        offspring[i] = if let Some(v) = last { v } else { s[i] };
    }

    for i in x2..s.len() {
        let mut o = mapping[s[i]];
        let mut last = None;
        while o.is_some() {
            last = o;
            o = mapping[o.unwrap()];
        }
        offspring[i] = if let Some(v) = last { v } else { s[i] };
    }

    TspTour {
        tour: offspring,
        cities: self.cities.clone(),
        rng_cell: self.rng_cell.clone(),
    }
}

Hi, thanks for sharing this gist, I actually included your code in my project: https://github.com/matiasmicheletto/dna-solver.
Cheers!