Example6.java Source code

Introduction

Here is the source code for Example6.java

Source

/* Copyright 2009-2016 David Hadka
 *
 * This file is part of the MOEA Framework.
 *
 * The MOEA Framework is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 *
 * The MOEA Framework is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the MOEA Framework.  If not, see <http://www.gnu.org/licenses/>.
 */
import java.io.File;
import java.io.IOException;

import org.apache.commons.lang3.SystemUtils;
import org.moeaframework.Executor;
import org.moeaframework.core.NondominatedPopulation;
import org.moeaframework.core.Solution;
import org.moeaframework.core.variable.RealVariable;
import org.moeaframework.problem.ExternalProblem;

/**
 * Similar to Example4, sockets can be used instead of standard I/O for
 * communicating with the external process.  Run the command 'make' in the
 * ./examples/ folder to compile the executable.  This example will only
 * work on POSIX (Unix-like) systems.
 */
public class Example6 {

    /**
     * Notice that the only change is in the constructor, where the hostname and
     * port are specified.
     */
    public static class MyDTLZ2 extends ExternalProblem {

        public MyDTLZ2() throws IOException {
            super("localhost", ExternalProblem.DEFAULT_PORT);
        }

        @Override
        public String getName() {
            return "DTLZ2";
        }

        @Override
        public int getNumberOfVariables() {
            return 11;
        }

        @Override
        public int getNumberOfObjectives() {
            return 2;
        }

        @Override
        public int getNumberOfConstraints() {
            return 0;
        }

        @Override
        public Solution newSolution() {
            Solution solution = new Solution(getNumberOfVariables(), getNumberOfObjectives());

            for (int i = 0; i < getNumberOfVariables(); i++) {
                solution.setVariable(i, new RealVariable(0.0, 1.0));
            }

            return solution;
        }

    }

    public static void main(String[] args) throws IOException, InterruptedException {
        //check if the executable exists
        File file = new File("./examples/dtlz2_socket.exe");

        if (!file.exists()) {
            if (!SystemUtils.IS_OS_UNIX) {
                System.err.println(
                        "This example only works on POSIX-compliant systems; see the Makefile for details");
                return;
            }

            System.err.println("Please compile the executable by running make in the ./examples/ folder");
            return;
        }

        //run the executable and wait one second for the process to startup
        new ProcessBuilder(file.toString()).start();
        Thread.sleep(1000);

        //configure and run the DTLZ2 function
        NondominatedPopulation result = new Executor().withProblemClass(MyDTLZ2.class).withAlgorithm("NSGAII")
                .withMaxEvaluations(10000).run();

        //display the results
        System.out.format("Objective1  Objective2%n");

        for (Solution solution : result) {
            System.out.format("%.4f      %.4f%n", solution.getObjective(0), solution.getObjective(1));
        }
    }

}