net.sourceforge.cilib.entity.operators.creation.RandToBestCreationStrategy Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of cilib-library Show documentation
A library of composable components enabling simpler Computational Intelligence
There is a newer version: 0.8
/**           __  __
 *    _____ _/ /_/ /_    Computational Intelligence Library (CIlib)
 *   / ___/ / / / __ \   (c) CIRG @ UP
 *  / /__/ / / / /_/ /   http://cilib.net
 *  \___/_/_/_/_.___/
 */
package net.sourceforge.cilib.entity.operators.creation;

import java.util.List;
import net.sourceforge.cilib.controlparameter.ConstantControlParameter;
import net.sourceforge.cilib.controlparameter.ControlParameter;
import net.sourceforge.cilib.entity.Entity;
import net.sourceforge.cilib.entity.Topologies;
import net.sourceforge.cilib.entity.Topology;
import net.sourceforge.cilib.type.types.container.Vector;
import net.sourceforge.cilib.util.selection.Samples;
import net.sourceforge.cilib.util.selection.Selection;
import net.sourceforge.cilib.util.selection.arrangement.RandomArrangement;

/**
 * This is an implementation of the Rand-to-best DE  target creation strategy. This implementation is simply an extension of the {@linkplain RandCreationStrategy} that also includes the best {@linkplain Entity}'s solution vector. The influence of the best vector and the
 * random vector is determined by the greedynessParameter, which is sampled as E [0,1]. A value of 0 will ignore the contribution of the best {@linkplain Entity}, and a
 * value of 1 will ignore the contribution of the random {@linkplain Entity}.
 */
public class RandToBestCreationStrategy extends RandCreationStrategy {

    private static final long serialVersionUID = 413628791093573875L;
    private ControlParameter greedynessParameter;

    /**
     * Create a new instance of {@code RandToBestCreationStrategy}.
     */
    public RandToBestCreationStrategy() {
        greedynessParameter = ConstantControlParameter.of(0.5);
    }

    /**
     * Copy constructor. Create a copy of the provided instance.
     * @param copy The instance to copy.
     */
    public RandToBestCreationStrategy(RandToBestCreationStrategy other) {
        super(other);
        greedynessParameter = other.greedynessParameter.getClone();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public  T create(T targetEntity, T current, Topology topology) {
        T bestEntity = Topologies.getBestEntity(topology);
        List participants = Selection.copyOf(topology)
                .exclude(targetEntity, bestEntity, current)
                .orderBy(new RandomArrangement())
                .select(Samples.first((int) numberOfDifferenceVectors.getParameter()).unique());
        Vector differenceVector = determineDistanceVector(participants);

        Vector targetVector = ((Vector) targetEntity.getCandidateSolution()).multiply(1 - greedynessParameter.getParameter());
        Vector bestVector = ((Vector) bestEntity.getCandidateSolution()).multiply(greedynessParameter.getParameter());

        Vector trialVector = bestVector.plus(targetVector.plus(differenceVector.multiply(scaleParameter.getParameter())));

        T trialEntity = (T) current.getClone();
        trialEntity.setCandidateSolution(trialVector);

        return trialEntity;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public RandToBestCreationStrategy getClone() {
        return new RandToBestCreationStrategy(this);
    }

    public void setGreedynessParameter(ControlParameter greedynessParameter) {
        this.greedynessParameter = greedynessParameter;
    }

    public ControlParameter getGreedynessParameter() {
        return greedynessParameter;
    }
}