/*
* This file is part of JGAP.
*
* JGAP offers a dual license model containing the LGPL as well as the MPL.
*
* For licensing information please see the file license.txt included with JGAP
* or have a look at the top of class org.jgap.Chromosome which representatively
* includes the JGAP license policy applicable for any file delivered with JGAP.
*/
package org.jgap.impl.salesman;
import org.jgap.*;
/**
* The fitness function to solve the Travelling Salesman problem. The function
* returned by this method calls {@link org.jgap.impl.salesman.Salesman#distance
* distance(Object from, Object to) }
*
* @author Audrius Meskauskas
* @since 2.0
*/
public class SalesmanFitnessFunction
extends FitnessFunction {
/** String containing the CVS revision. Read out via reflection!*/
private final static String CVS_REVISION = "$Revision: 1.10 $";
private final Salesman m_salesman;
public SalesmanFitnessFunction(final Salesman a_salesman) {
m_salesman = a_salesman;
}
/**
* Computes the distance by calling salesman
* {@link org.jgap.impl.salesman.Salesman#distance(org.jgap.Gene, org.jgap.Gene) }
*
* @param a_subject chromosome representing cities
* @return distance of the journey thru the cities represented in the
* given chromosome
*
* @author Audrius Meskauskas
* @since 2.0
*/
protected double evaluate(final IChromosome a_subject) {
double s = 0;
Gene[] genes = a_subject.getGenes();
for (int i = 0; i < genes.length - 1; i++) {
s += m_salesman.distance(genes[i], genes[i + 1]);
}
// add cost of coming back:
s += m_salesman.distance(genes[genes.length - 1], genes[0]);
return Integer.MAX_VALUE / 2 - s;
}
}