Example5.java

/* Copyright 2009-2015 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.moeaframework.Executor;
import org.moeaframework.core.NondominatedPopulation;
import org.moeaframework.core.Solution;
import org.moeaframework.core.variable.RealVariable;
import org.moeaframework.problem.ExternalProblem;

/**
 * Demonstrates how problems can be defined externally to the MOEA Framework,
 * possibly written in a different programming language.  In this case, the
 * problem is defined in the file ./examples/dtlz2.c using the C programming
 * language.  Run the command 'make' in the ./examples/ folder to compile
 * the executable.
 */
public class Example5 {

	/**
	 * The ExternalProblem opens a communication channel with the external
	 * process defined in the constructor.
	 */
	public static class MyDTLZ2 extends ExternalProblem {

		public MyDTLZ2() throws IOException {
			super("./examples/dtlz2_stdio.exe");
		}

		@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) {
		//check if the executable exists
		File file = new File("./examples/dtlz2_stdio.exe");
				
		if (!file.exists()) {
			System.err.println("Please compile the executable by running make in the ./examples/ folder");
			return;
		}
		
		//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));
		}
	}
	
}