eva2/src/eva2/optimization/operator/crossover/CrossoverESSBX.java

package eva2.optimization.operator.crossover;

import eva2.gui.plot.Plot;
import eva2.optimization.individuals.AbstractEAIndividual;
import eva2.optimization.individuals.ESIndividualDoubleData;
import eva2.optimization.individuals.InterfaceESIndividual;
import eva2.optimization.population.Population;
import eva2.problems.F1Problem;
import eva2.problems.InterfaceOptimizationProblem;
import eva2.tools.math.RNG;
import eva2.util.annotation.Description;

/**
 *
 */
@Description("The SBX crossover simulates a binary crossover (works only for two partners!).")
public class CrossoverESSBX implements InterfaceCrossover, java.io.Serializable {

    private InterfaceOptimizationProblem optimizationProblem;
    private double eta = 0.2;

    public CrossoverESSBX() {

    }

    public CrossoverESSBX(double eta) {
        this.eta = eta;
    }

    public CrossoverESSBX(CrossoverESSBX c) {
        this.optimizationProblem = c.optimizationProblem;
        this.eta = c.eta;
    }

    /**
     * This method will enable you to clone a given mutation operator
     *
     * @return The clone
     */
    @Override
    public Object clone() {
        return new CrossoverESSBX(this);
    }

    /**
     * This method performs crossover on two individuals. If the individuals do
     * not implement InterfaceGAIndividual, then nothing will happen.
     *
     * @param indy1    The first individual
     * @param partners The second individual
     */
    @Override
    public AbstractEAIndividual[] mate(AbstractEAIndividual indy1, Population partners) {
        AbstractEAIndividual[] result = null;
        double[][] parents, children;
        double beta, u;

        result = new AbstractEAIndividual[partners.size() + 1];
        result[0] = (AbstractEAIndividual) (indy1).clone();
        for (int i = 0; i < partners.size(); i++) {
            result[i + 1] = (AbstractEAIndividual) ((AbstractEAIndividual) partners.get(i)).clone();
        }
        //for (int i = 0; i < result.length; i++) System.out.println("Before Crossover: " +result[i].getSolutionRepresentationFor());

        if ((indy1 instanceof InterfaceESIndividual) && (partners.get(0) instanceof InterfaceESIndividual)) {
            parents = new double[partners.size() + 1][];
            children = new double[partners.size() + 1][];
            for (int i = 0; i < result.length; i++) {
                parents[i] = new double[((InterfaceESIndividual) result[i]).getDGenotype().length];
                children[i] = new double[parents[i].length];
                System.arraycopy(((InterfaceESIndividual) result[i]).getDGenotype(), 0, parents[i], 0, parents[i].length);
                System.arraycopy(((InterfaceESIndividual) result[i]).getDGenotype(), 0, children[i], 0, parents[i].length);
            }

            for (int i = 0; i < children[0].length; i++) {
                u = RNG.randomDouble(0, 1);
                if (u <= 0.5) {
                    beta = Math.pow((2 * u), 1 / (this.eta + 1));
                } else {
                    beta = Math.pow((0.5 / (1 - u)), 1 / (this.eta + 1));
                }
                children[0][i] = 0.5 * ((1 + beta) * parents[0][i] + (1 - beta) * parents[1][i]);
                children[1][i] = 0.5 * ((1 - beta) * parents[0][i] + (1 + beta) * parents[1][i]);
            }
            // write the result back
            for (int i = 0; i < result.length; i++) {
                ((InterfaceESIndividual) result[i]).setDGenotype(children[i]);
            }
        }
        //in case the crossover was successfull lets give the mutation operators a chance to mate the strategy parameters
        for (int i = 0; i < result.length; i++) {
            result[i].getMutationOperator().crossoverOnStrategyParameters(indy1, partners);
        }
        //for (int i = 0; i < result.length; i++) System.out.println("After Crossover: " +result[i].getSolutionRepresentationFor());
        return result;
    }

    /**
     * This method allows you to evaluate wether two crossover operators
     * are actually the same.
     *
     * @param crossover The other crossover operator
     */
    @Override
    public boolean equals(Object crossover) {
        if (crossover instanceof CrossoverESSBX) {
            CrossoverESSBX cross = (CrossoverESSBX) crossover;
            return this.eta == cross.eta;
        } else {
            return false;
        }
    }

    /**
     * This method will allow the crossover operator to be initialized depending on the
     * individual and the optimization problem. The optimization problem is to be stored
     * since it is to be called during crossover to calculate the exogene parameters for
     * the offsprings.
     *
     * @param individual The individual that will be mutated.
     * @param opt        The optimization problem.
     */
    @Override
    public void init(AbstractEAIndividual individual, InterfaceOptimizationProblem opt) {
        this.optimizationProblem = opt;
    }

    public static void main(String[] args) {
        Population pop = new Population();
        double[] tmpD = new double[2];
        ESIndividualDoubleData indy1, indy2, indy3;
        F1Problem prob = new F1Problem();

        // initialize individual
        indy1 = new ESIndividualDoubleData();
        double[][] range = new double[2][2];
        range[0][0] = -2.0;
        range[0][1] = 2.0;
        range[1][0] = -2.0;
        range[1][1] = 2.0;
        indy1.setDoubleDataLength(2);
        indy1.setDoubleRange(range);
        // initialize values
        indy2 = (ESIndividualDoubleData) indy1.clone();
        indy3 = (ESIndividualDoubleData) indy1.clone();
        if (false) {
            // random initialize
            indy1.defaultInit(prob);
            indy2.defaultInit(prob);
            indy3.defaultInit(prob);
        } else {
            // value initialize
            tmpD[0] = 0.5;
            tmpD[1] = -0.5;
            indy1.initByValue(tmpD, prob);
            tmpD[0] = -0.5;
            tmpD[1] = 0.5;
            indy2.initByValue(tmpD, prob);
            tmpD[0] = -0.5;
            tmpD[1] = 1;
            indy3.initByValue(tmpD, prob);
        }
        // set the parents
        pop.add(indy2);
        pop.add(indy3);
        tmpD[0] = 1;
        tmpD[1] = 1;
        Plot plot = new Plot("SBX Test", "x", "y", true);
        tmpD = indy1.getDoubleData();
        plot.setUnconnectedPoint(tmpD[0], tmpD[1], 0);
        tmpD = indy2.getDoubleData();
        plot.setUnconnectedPoint(tmpD[0], tmpD[1], 0);
        tmpD = indy3.getDoubleData();
        plot.setUnconnectedPoint(tmpD[0], tmpD[1], 0);
        plot.setUnconnectedPoint(-2, -2, 0);
        plot.setUnconnectedPoint(2, 2, 0);
        plot.setUnconnectedPoint(2, 2, 0);

        CrossoverESSBX cross = new CrossoverESSBX();
        cross.eta = 0.2;
        AbstractEAIndividual[] offsprings;
        for (int i = 0; i < 5000; i++) {
            offsprings = cross.mate(indy1, pop);
            for (int j = 0; j < offsprings.length; j++) {
                tmpD = ((ESIndividualDoubleData) offsprings[j]).getDoubleData();
                plot.setUnconnectedPoint(tmpD[0], tmpD[1], 1);
                //range = ((ESIndividualDoubleData)offsprings[j]).getDoubleRange();
                //System.out.println("["+range[0][0]+"/"+range[0][1]+";"+range[1][0]+"/"+range[1][1]+"]");
            }
        }
    }

    @Override
    public String getStringRepresentation() {
        return this.getName();
    }

    /**
     * This method allows the CommonJavaObjectEditorPanel to read the
     * name to the current object.
     *
     * @return The name.
     */
    public String getName() {
        return "ES SBX crossover";
    }

    /**
     * This method allows you to set the number of crossovers that occur in the
     * genotype.
     *
     * @param a The number of crossovers.
     */
    public void setEta(double a) {
        if (a < 0) {
            a = 0;
        }
        this.eta = a;
    }

    public double getEta() {
        return this.eta;
    }

    public String etaTipText() {
        return "Set the Eta_c value (the larger the value, the more restricted the search).";
    }
}