/**
* Copyright (C) 2010-2017 Gordon Fraser, Andrea Arcuri and EvoSuite
* contributors
*
* This file is part of EvoSuite.
*
* EvoSuite is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3.0 of the License, or
* (at your option) any later version.
*
* EvoSuite is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>.
*/
package org.evosuite.ga.comparators;
import java.io.Serializable;
import java.util.Comparator;
import org.evosuite.ga.Chromosome;
import org.evosuite.ga.FitnessFunction;
/**
* Sort a Collection of Chromosomes by their Dominance
*
* @author José Campos
*/
public class DominanceComparator
implements Comparator<Chromosome>, Serializable
{
/**
*
*/
private static final long serialVersionUID = -3962098107892633870L;
/**
* Is c2 dominated by c1?
*
* http://en.wikipedia.org/wiki/Multi-objective_optimization#Introduction
*
* @param c1
* @param c2
* @return -1, or 0, or 1 if solution1 dominates solution2, both are non-dominated, or solution1 is dominated by
* solution2, respectively.
*/
@Override
public int compare(Chromosome c1, Chromosome c2)
{
int dominate1 = 0;
int dominate2 = 0;
int flag; // stores the result of the comparison
for (FitnessFunction<?> ff : c1.getFitnessValues().keySet()) {
double value1 = c1.getFitness(ff);
double value2 = c2.getFitness(ff);
if (value1 < value2)
flag = -1;
else if (value1 > value2)
flag = 1;
else
flag = 0;
if (flag == -1)
dominate1 = 1;
if (flag == 1)
dominate2 = 1;
}
if (dominate1 == dominate2)
return 0; // no one dominate the other
if (dominate1 == 1)
return -1; // chromosome1 dominate
return 1; // chromosome2 dominate
}
}