genetic algorithm experiment

guess.scala

import scala.language.postfixOps
import scala.util.Random

class Guess {
  class GeneticSolver {
    def getBest(toMatch: String) = {
      def random: Stream[Char] = toMatch(Random.nextInt(toMatch.length)) #:: random

      def iterate(parent: Seq[Char], score: Int, generation: Int): Seq[Char] = if (score != toMatch.length) {
        def mutate = parent.updated(Random.nextInt(toMatch.length), toMatch(Random.nextInt(toMatch.length)))

        val child = mutate
        val childScore = getFitness(child)

        if (childScore > score) {
          println(s"generation\t${generation + 1}\tfitness\t${childScore}\t${child.mkString}")

          iterate(child, childScore, generation + 1)
        } else iterate(parent, score, generation + 1)
      } else parent

      def getFitness(seq: Seq[Char]) = (0 until toMatch.length) count { i =>
        toMatch(i) == seq(i)
      }

      val init = random take toMatch.length
      val score = getFitness(init)

      println(s"generation\t1\tfitness\t${score}\t${init.mkString}")

      iterate(init, score, 1)
    }
  }

  class StringDuplicator {
    def duplicate(toMatch: String) = new GeneticSolver().getBest(toMatch)
  }

  println(new StringDuplicator().duplicate("hello world!") mkString)
}

new Guess()