net.sourceforge.cilib.pso.dynamic.HigherLevelChangedDynamicIterationStrategy 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.pso.dynamic;

import net.sourceforge.cilib.algorithm.AbstractAlgorithm;
import net.sourceforge.cilib.algorithm.population.PopulationBasedAlgorithm;
import net.sourceforge.cilib.algorithm.population.RespondingMultiPopulationCriterionBasedAlgorithm;

/**
 * Dynamic iteration strategy for PSO in dynamic environments used by a
 * higher level algorithm, e.g. VEPSO, that has a number of sub-algorithms.
 * In each iteration, it checks for an environmental change in each
 * swarm. If a change has been detected in a swarm, it responds to
 * the change according to the selected response strategy.
 *
 *
 * @param  The {@link PopulationBasedAlgorithm} that will have it's entities'
 * positions added to the archive as potential solutions.
 */
public class HigherLevelChangedDynamicIterationStrategy  extends HigherLevelDynamicIterationStrategy {

    private static final long serialVersionUID = -4417977245641438303L;

    /**
     * Structure of Higher Level Dynamic Iteration Strategy with re-initialisation:
     *
     * 
     *   Check for environment change in any of the swarms
     *   If the environment has changed:
     *   
     *     Respond to change for all swarms
     *   
     *   Perform normal iteration for all swarms
     * 
     */
    @Override
    public void performIteration(PopulationBasedAlgorithm algorithm) {
    	//get the higher level algorithm
    	RespondingMultiPopulationCriterionBasedAlgorithm topLevelAlgorithm =
    		(RespondingMultiPopulationCriterionBasedAlgorithm)
    			AbstractAlgorithm.getAlgorithmList().get(0);

        boolean hasChanged = false;

        //detecting whether a change has occurred in any of the swarms' environment
    	for (PopulationBasedAlgorithm popAlg: topLevelAlgorithm.getPopulations()) {
            hasChanged = this.getDetectionStrategy().detect(popAlg);
            if (hasChanged)
                break;
    	}

        if (hasChanged) {
            for (PopulationBasedAlgorithm popAlg: topLevelAlgorithm.getPopulations()) {
                boolean functionHasChanged = this.getDetectionStrategy().detect(popAlg);
    		if (functionHasChanged) {
                    this.getResponseStrategy().respond(popAlg);
    		}
            }
        }

        for (PopulationBasedAlgorithm popAlg: topLevelAlgorithm.getPopulations()) {
            popAlg.performIteration();
    	}
    }

}