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A library of composable components enabling simpler Computational Intelligence

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/**           __  __
 *    _____ _/ /_/ /_    Computational Intelligence Library (CIlib)
 *   / ___/ / / / __ \   (c) CIRG @ UP
 *  / /__/ / / / /_/ /   http://cilib.net
 *  \___/_/_/_/_.___/
 */
package net.sourceforge.cilib.entity.comparator;

import java.io.Serializable;
import java.util.Comparator;
import net.sourceforge.cilib.controlparameter.ControlParameter;
import net.sourceforge.cilib.controlparameter.LinearlyVaryingControlParameter;
import net.sourceforge.cilib.controlparameter.UpdateOnIterationControlParameter;
import net.sourceforge.cilib.entity.Entity;
import net.sourceforge.cilib.math.random.ProbabilityDistributionFunction;
import net.sourceforge.cilib.math.random.UniformDistribution;

public class BoltzmannComparator implements Comparator, Serializable {
    
    private ProbabilityDistributionFunction distribution;
    private ControlParameter tempSchedule;
    
    public BoltzmannComparator() {
        this.distribution = new UniformDistribution();

        LinearlyVaryingControlParameter cp = new LinearlyVaryingControlParameter();
        cp.setInitialValue(100);
        cp.setFinalValue(1);

        UpdateOnIterationControlParameter outerCP = new UpdateOnIterationControlParameter();
        outerCP.setDelegate(cp);
        
        this.tempSchedule = outerCP;
    }

    @Override
    public int compare(E t, E t1) {
        int sign = -t.compareTo(t1);
        double diff = Math.abs(t.getFitness().getValue() - t1.getFitness().getValue());
        double probability = 1 / (1 + Math.exp(sign * diff / tempSchedule.getParameter()));

        if (distribution.getRandomNumber() > probability) {
            return -1;
        }
        
        return 1;
    }

    public ProbabilityDistributionFunction getDistribution() {
        return distribution;
    }

    public void setDistribution(ProbabilityDistributionFunction distribution) {
        this.distribution = distribution;
    }

    public ControlParameter getTempSchedule() {
        return tempSchedule;
    }

    public void setTempSchedule(ControlParameter tempSchedule) {
        this.tempSchedule = tempSchedule;
    }
}