OffspringArchiveDominance.java

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package hh.creditassignment.offspringpopulation;

import hh.creditassigment.CreditDefinedOn;
import org.moeaframework.core.EpsilonBoxDominanceArchive;
import org.moeaframework.core.NondominatedPopulation;
import org.moeaframework.core.Population;
import org.moeaframework.core.Solution;

/**
 * This credit definition gives credit to the specified solution if it makes it
 * in the epsilon archive. Credit is only assigned to the specified solution.
 * @author nozomihitomi
 */
public class OffspringArchiveDominance extends AbstractOffspringPopulation{
    /**
     * Credit received if a new solution is in the archive 
     */
    protected final double inArchive;
    
    /**
     * Credit received if a new solution is not in the archive 
     */
    protected final double notInArchive;
    
    /**
     * The constructor needs the value for credit when a solution is in the 
     * e-archive and for when a solution is not in the e-archive
     * @param inArchive credit to assign when solution is in the archive 
     * @param notInArchive credit to assign when solution is not in the archive 
     */
    public OffspringArchiveDominance(double inArchive, double notInArchive) {
        operatesOn = CreditDefinedOn.ARCHIVE;
        this.notInArchive = notInArchive;
        this.inArchive = inArchive;
    }
    
    /**
     * Adds the offspring solution to the archive to see if the Pareto front changes. If it changes, the heuristic will receive a reward
     * @param offspring solution that will receive credits
     * @param archive the archive to compare the offspring solutions with
     * @return the value of credit to resulting from the solution
     */
    @Override
    public double compute(Solution offspring, Population archive) {
        if(!archive.getClass().equals(EpsilonBoxDominanceArchive.class))
            throw new ClassCastException("Need to be NondominatedPopulation: " + archive.getClass());
        EpsilonBoxDominanceArchive ndpop = (EpsilonBoxDominanceArchive)archive;
        if(ndpop.add(offspring))
            return inArchive;
        else
            return notInArchive;
    }
    
    @Override
    public String toString() {
        return "SI-A";
    }
    
}