net.sourceforge.cilib.ec.iterationstrategies.GeneticAlgorithmIterationStrategy Maven / Gradle / Ivy

Go to download
/**           __  __
 *    _____ _/ /_/ /_    Computational Intelligence Library (CIlib)
 *   / ___/ / / / __ \   (c) CIRG @ UP
 *  / /__/ / / / /_/ /   http://cilib.net
 *  \___/_/_/_/_.___/
 */
package net.sourceforge.cilib.ec.iterationstrategies;

import java.util.List;
import net.sourceforge.cilib.algorithm.population.AbstractIterationStrategy;
import net.sourceforge.cilib.algorithm.population.IterationStrategy;
import net.sourceforge.cilib.ec.EC;
import net.sourceforge.cilib.ec.Individual;
import net.sourceforge.cilib.entity.Entity;
import net.sourceforge.cilib.entity.operators.CrossoverOperator;
import net.sourceforge.cilib.entity.operators.crossover.CrossoverStrategy;
import net.sourceforge.cilib.entity.operators.crossover.UniformCrossoverStrategy;
import net.sourceforge.cilib.entity.operators.mutation.GaussianMutationStrategy;
import net.sourceforge.cilib.entity.operators.mutation.MutationStrategy;

import com.google.common.collect.Lists;

/**
 * TODO: Complete this javadoc.
 */
public class GeneticAlgorithmIterationStrategy extends AbstractIterationStrategy {

    private static final long serialVersionUID = -2429984051022079804L;
    private CrossoverOperator crossover;
    private MutationStrategy mutationStrategy;

    /**
     * Create an instance of the {@linkplain IterationStrategy}. Default cross-over
     * and mutation operators are {@linkplain UniformCrossoverStrategy} and
     * {@linkplain GaussianMutationStrategy} respectively.
     */
    public GeneticAlgorithmIterationStrategy() {
        this.crossover = new CrossoverOperator();
        this.crossover.setCrossoverStrategy(new UniformCrossoverStrategy());
        this.mutationStrategy = new GaussianMutationStrategy();
    }

    /**
     * Copy constructor. Create an instance that is a copy of the provided instance.
     * @param copy the instance to copy.
     */
    public GeneticAlgorithmIterationStrategy(GeneticAlgorithmIterationStrategy copy) {
        this.crossover = copy.crossover.getClone();
        this.mutationStrategy = copy.mutationStrategy.getClone();
    }

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

    /**
     * {@inheritDoc}
     *
     * @param ec The EC algorithm to perform the iteration on.
     */
    @Override
    public void performIteration(EC ec) {
        fj.data.List population = ec.getTopology();

        // Perform crossover: Allow each individual to create an offspring
        List crossedOver = Lists.newArrayList();
        for (int i = 0, n = population.length(); i < n; i++) {
            crossedOver.addAll(crossover.crossover(ec.getTopology()));
        }

        // Perform mutation on offspring
        mutationStrategy.mutate(crossedOver);

        // Evaluate the fitness values of the generated offspring
        for (Entity entity : crossedOver) {
            boundaryConstraint.enforce(entity);
            entity.calculateFitness();
        }

        // Perform new population selection
        fj.data.List local = ec.getTopology().append(fj.data.List.iterableList(crossedOver))
            .sort(Individual.ordering);

        ec.setTopology(local.take(ec.getInitialisationStrategy().getEntityNumber()));
    }

    /**
     * Get the currently specified {@linkplain CrossoverStrategy}.
     * @return The current {@linkplain CrossoverStrategy}.
     */
    public CrossoverOperator getCrossover() {
        return crossover;
    }

    /**
     * Set the current {@linkplain CrossoverStrategy} and reinitialise the operator pipeline.
     * @param crossoverStrategy The {@linkplain CrossoverStrategy} to use.
     */
    public void setCrossover(CrossoverOperator crossoverStrategy) {
        this.crossover = crossoverStrategy;
    }

    /**
     * Get the currently specified {@linkplain MutationStrategy}.
     * @return The current {@linkplain MutationStrategy}.
     */
    public MutationStrategy getMutationStrategy() {
        return mutationStrategy;
    }

    /**
     * Set the current {@linkplain MutationStrategy} and reinitialise the operator pipeline.
     * @param mutationStrategy The {@linkplain MutationStrategy} to use.
     */
    public void setMutationStrategy(MutationStrategy mutationStrategy) {
        this.mutationStrategy = mutationStrategy;
    }
}