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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.pso.iterationstrategies;

import net.sourceforge.cilib.algorithm.population.AbstractIterationStrategy;
import net.sourceforge.cilib.entity.Topology;
import net.sourceforge.cilib.pso.PSO;
import net.sourceforge.cilib.pso.particle.Particle;

/**
 * Implementation of the synchronous iteration strategy for PSO.
 */
public class SynchronousIterationStrategy extends AbstractIterationStrategy {

    private static final long serialVersionUID = 6617737228912852220L;

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

    /**
     * This is an Synchronous strategy:
     * 
     * For all particles:
     * Update the particle velocity
     *     Update the particle position
     * For all particles:
     * Calculate the particle fitness
     *     For all particles in the current particle's neighbourhood:
     *     Update the neighbourhood best
     * 
     *
     * @see net.sourceforge.cilib.PSO.IterationStrategy#performIteration(net.sourceforge.cilib.PSO.PSO)
     * @param pso The {@link PSO} to have an iteration applied.
     */
    @Override
    public void performIteration(PSO pso) {
        Topology topology = pso.getTopology();

        for (Particle current : topology) {
            current.updateVelocity();
            current.updatePosition(); // TODO: replace with visitor (will simplify particle interface)

            boundaryConstraint.enforce(current);
        }

        for (Particle current : topology) {
            current.calculateFitness();
            for (Particle other : topology.neighbourhood(current)) {
                if (current.getSocialFitness().compareTo(other.getNeighbourhoodBest().getSocialFitness()) > 0) {
                    other.setNeighbourhoodBest(current);
                }
            }
        }
    }
}