/*
* 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 examples.simpleBoolean;
import org.jgap.*;
import org.jgap.impl.*;
/**
* Fitness function for our example. See evaluate(...) method for details.
*
* @author Neil Rotstan
* @author Klaus Meffert
* @since 2.0
*/
public class MaxFunction
extends FitnessFunction {
/** String containing the CVS revision. Read out via reflection!*/
private final static String CVS_REVISION = "$Revision: 1.6 $";
/**
* This example implementation calculates the fitness value of Chromosomes
* using BooleanAllele implementations. It simply returns a fitness value
* equal to the numeric binary value of the bits. In other words, it
* optimizes the numeric value of the genes interpreted as bits. It should
* be noted that, for clarity, this function literally returns the binary
* value of the Chromosome's genes interpreted as bits. However, it would
* be better to return the value raised to a fixed power to exaggerate the
* difference between the higher values. For example, the difference
* between 254 and 255 is only about .04%, which isn't much incentive for
* the selector to choose 255 over 254. However, if you square the values,
* you then get 64516 and 65025, which is a difference of 0.8% -- twice
* as much and, therefore, twice the incentive to select the higher
* value.
*
* @param a_subject the Chromosome to be evaluated
* @return defect rate of our problem
*
* @author Neil Rotstan
* @author Klaus Meffert
* @since 2.0
*/
public double evaluate(IChromosome a_subject) {
int total = 0;
for (int i = 0; i < a_subject.size(); i++) {
BooleanGene value = (BooleanGene) a_subject.getGene(a_subject.size() -
(i + 1));
if (value.booleanValue()) {
total += Math.pow(2.0, (double) i);
}
}
return total;
}
}