com.dlej.Main.java Source code

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Here is the source code for com.dlej.Main.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.dlej;

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.RandomStringUtils;
import org.apache.commons.math3.genetics.Chromosome;
import org.apache.commons.math3.genetics.ElitisticListPopulation;
import org.apache.commons.math3.genetics.GeneticAlgorithm;
import org.apache.commons.math3.genetics.OnePointCrossover;
import org.apache.commons.math3.genetics.Population;
import org.apache.commons.math3.genetics.StoppingCondition;
import org.apache.commons.math3.genetics.TournamentSelection;
import org.apache.commons.math3.util.Precision;

public class Main {
    public static final int POPULATION_SIZE = 1000;
    public static final double CROSSOVER_RATE = 0.9;
    public static final double MUTATION_RATE = 0.03;
    public static final double ELITISM_RATE = 0.1;
    public static final int TOURNAMENT_ARITY = 2;

    public static final String TARGET_STRING = "Hello World!";
    public static final int DIMENSION = TARGET_STRING.length();

    public static void main(String[] args) {
        long startTime = System.currentTimeMillis();

        // initialize a new genetic algorithm
        GeneticAlgorithm ga = new GeneticAlgorithm(new OnePointCrossover<Character>(), CROSSOVER_RATE,
                new RandomCharacterMutation(), MUTATION_RATE, new TournamentSelection(TOURNAMENT_ARITY));

        // initial population
        Population initial = getInitialPopulation();

        // stopping condition
        StoppingCondition stoppingCondition = new StoppingCondition() {

            int generation = 0;

            @Override
            public boolean isSatisfied(Population population) {
                Chromosome fittestChromosome = population.getFittestChromosome();

                if (generation == 1 || generation % 10 == 0) {
                    System.out.println("Generation " + generation + ": " + fittestChromosome.toString());
                }
                generation++;

                double fitness = fittestChromosome.fitness();
                if (Precision.equals(fitness, 0.0, 1e-6)) {
                    return true;
                } else {
                    return false;
                }
            }
        };

        System.out.println("Starting evolution ...");

        // run the algorithm
        Population finalPopulation = ga.evolve(initial, stoppingCondition);

        // Get the end time for the simulation.
        long endTime = System.currentTimeMillis();

        // best chromosome from the final population
        Chromosome best = finalPopulation.getFittestChromosome();
        System.out.println("Generation " + ga.getGenerationsEvolved() + ": " + best.toString());
        System.out.println("Total execution time: " + (endTime - startTime) + "ms");
    }

    private static List<Character> randomRepresentation(int length) {
        return asList(RandomStringUtils.randomAscii(length));
    }

    public static List<Character> asList(String str) {
        return Arrays.asList(ArrayUtils.toObject(str.toCharArray()));
    }

    public static Population getInitialPopulation() {
        List<Chromosome> popList = new LinkedList<Chromosome>();

        for (int i = 0; i < POPULATION_SIZE; i++) {
            popList.add(new StringChromosome(randomRepresentation(DIMENSION)));
        }
        return new ElitisticListPopulation(popList, 2 * popList.size(), ELITISM_RATE);
    }
}