particleupdatesimple.java

這是最近蒐集資料找到的Java PSO Swarm 大家可以下載回去參考使用 理面文件有原出處以及作者 請大家要記得尊重版權

package net.sourceforge.jswarm_pso;

/**
 * Particle update strategy
 * 
 * Every Swarm.evolve() itereation the following methods are called
 * 		- begin(Swarm) : Once at the begining of each iteration
 * 		- update(Swarm,Particle) : Once for each particle
 * 		- end(Swarm) : Once at the end of each iteration
 * 
 * @author Pablo Cingolani <[e-mail]>
 */
public class ParticleUpdateSimple extends ParticleUpdate {
	
	/** Random vector for local update */
	double rlocal[];
	/** Random vector for global update */
	double rglobal[];

	/**
	 * Constructor 
	 * @param particle : Sample of particles that will be updated later
	 */
	public ParticleUpdateSimple(Particle particle) {
		super(particle);
		rlocal = new double[particle.getDimention()];
		rglobal = new double[particle.getDimention()];
	}
	
	/** 
	 * This method is called at the begining of each iteration
	 * Initialize random vectors use for local and global updates (rlocal[] and rother[])
	 */
	public void begin(Swarm swarm) {
		int i,dim = swarm.getSampleParticle().getDimention();
		for( i=0 ; i < dim ; i++ ) {
			rlocal[i] = Math.random();
			rglobal[i] = Math.random();
		}
	}
	
	/** Update particle's velocity and position */
	public void update(Swarm swarm, Particle particle) {
		double position[] = particle.getPosition();
		double velocity[] = particle.getVelocity();
		double globalBestPosition[] = swarm.getBestPosition();
		double particleBestPosition[] = particle.getBestPosition();
		
		// Update velocity and position
		for( int i = 0; i < position.length; i++ ) {
			// Update velocity
			velocity[i] = swarm.getInertia() * velocity[i] // Inertia
					+ rlocal[i] * swarm.getParticleIncrement() * (particleBestPosition[i] - position[i]) // Local best
					+ rglobal[i] * swarm.getGlobalIncrement() * (globalBestPosition[i] - position[i]); // Global best
			// Update position
			position[i] += velocity[i];
		}
	}
	
	/** This method is called at the end of each iteration */
	public void end(Swarm swarm) {
	}
}