/*
  Portions copyright 2010 by Sean Luke, Robert Hubley, and George Mason University
  Licensed under the Academic Free License version 3.0
  See the file "LICENSE" for more information
*/

package ec.multiobjective.spea2;

import ec.*;
import ec.util.*;
import ec.multiobjective.*;
import ec.simple.*; 

/* 
 * SPEA2Evaluator.java
 * 
 * Created: Sat Oct 16 11:24:43 EDT 2010
 * By: Faisal Abidi and Sean Luke
 * Replaces earlier class by: Robert Hubley, with revisions by Gabriel Balan and Keith Sullivan
 */
 
/**
 * This subclass of SimpleEvaluator evaluates the population, then computes auxiliary fitness
 * data of each subpopulation.
 */

public class SPEA2Evaluator extends SimpleEvaluator
    {
    public void evaluatePopulation(final EvolutionState state)
        {
        super.evaluatePopulation(state);
                
        // build SPEA2 fitness values
        for(int x = 0;xarray[i]
        double tmp = array[i];
        array[i]=array[p];
        array[p]=tmp;
        return partition(array,p,r);
        }
                
                
    /* [cormen p 154] */
    int partition(double[] array, int p, int r)
        {
        double x = array[p];
        int i = p-1;
        int j = r+1;
        while(true)
            {
            do j--; while(array[j]>x);
            do i++; while(array[i]array[j]
                double tmp = array[i];
                array[i]=array[j];
                array[j]=tmp;
                }
            else
                return j;
            }
        }
    }