DoubleChromosomeMultiPointCrossover.java
package net.bmahe.genetics4j.core.combination.multipointcrossover;
import java.util.List;
import java.util.random.RandomGenerator;
import org.apache.commons.lang3.Validate;
import net.bmahe.genetics4j.core.chromosomes.Chromosome;
import net.bmahe.genetics4j.core.chromosomes.DoubleChromosome;
import net.bmahe.genetics4j.core.combination.ChromosomeCombinator;
import net.bmahe.genetics4j.core.spec.AbstractEAConfiguration;
import net.bmahe.genetics4j.core.spec.combination.MultiPointCrossover;
public class DoubleChromosomeMultiPointCrossover<T extends Comparable<T>> implements ChromosomeCombinator<T> {
private final RandomGenerator randomGenerator;
private final MultiPointCrossover multiPointCrossoverPolicy;
public DoubleChromosomeMultiPointCrossover(final RandomGenerator _randomGenerator,
final MultiPointCrossover _multiPointCrossoverPolicy) {
Validate.notNull(_randomGenerator);
Validate.notNull(_multiPointCrossoverPolicy);
this.randomGenerator = _randomGenerator;
this.multiPointCrossoverPolicy = _multiPointCrossoverPolicy;
}
@Override
public List<Chromosome> combine(final AbstractEAConfiguration<T> eaConfiguration, final Chromosome chromosome1,
final T firstParentFitness, final Chromosome chromosome2, final T secondParentFitness) {
Validate.notNull(chromosome1);
Validate.notNull(chromosome2);
Validate.isInstanceOf(DoubleChromosome.class, chromosome1);
Validate.isInstanceOf(DoubleChromosome.class, chromosome2);
Validate.isTrue(chromosome1.getNumAlleles() == chromosome2.getNumAlleles());
Validate.isTrue(multiPointCrossoverPolicy.numCrossovers() < chromosome1.getNumAlleles());
Validate.isTrue(multiPointCrossoverPolicy.numCrossovers() < chromosome2.getNumAlleles());
final int[] alleleSplits = randomGenerator.ints(0, chromosome1.getNumAlleles())
.distinct()
.limit(multiPointCrossoverPolicy.numCrossovers())
.sorted()
.toArray();
final DoubleChromosome doubleChromosome1 = (DoubleChromosome) chromosome1;
final DoubleChromosome doubleChromosome2 = (DoubleChromosome) chromosome2;
final int numAlleles = chromosome1.getNumAlleles();
final double[] firstChildValues = new double[numAlleles];
final double[] secondChildValues = new double[numAlleles];
boolean useChromosome1 = true;
int splitIndex = 0;
for (int i = 0; i < doubleChromosome1.getNumAlleles(); i++) {
if (splitIndex < alleleSplits.length && i == alleleSplits[splitIndex]) {
splitIndex++;
useChromosome1 = !useChromosome1;
}
if (useChromosome1) {
firstChildValues[i] = doubleChromosome1.getAllele(i);
secondChildValues[i] = doubleChromosome2.getAllele(i);
} else {
firstChildValues[i] = doubleChromosome2.getAllele(i);
secondChildValues[i] = doubleChromosome1.getAllele(i);
}
}
/**
* TODO Should the min/max values be extended based on the lowest/highest
* values?
*/
final double minValue = doubleChromosome1.getMinValue();
final double maxValue = doubleChromosome2.getMaxValue();
return List.of(new DoubleChromosome(numAlleles, minValue, maxValue, firstChildValues),
new DoubleChromosome(numAlleles, minValue, maxValue, secondChildValues));
}
}