IntChromosomeMultiPointArithmetic.java
package net.bmahe.genetics4j.core.combination.multipointarithmetic;
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.IntChromosome;
import net.bmahe.genetics4j.core.combination.ChromosomeCombinator;
import net.bmahe.genetics4j.core.spec.AbstractEAConfiguration;
import net.bmahe.genetics4j.core.spec.combination.MultiPointArithmetic;
public class IntChromosomeMultiPointArithmetic<T extends Comparable<T>> implements ChromosomeCombinator<T> {
private final RandomGenerator randomGenerator;
private final MultiPointArithmetic multiPointArithmeticPolicy;
public IntChromosomeMultiPointArithmetic(final RandomGenerator _randomGenerator,
final MultiPointArithmetic _multiPointArithmeticPolicy) {
Validate.notNull(_randomGenerator);
Validate.notNull(_multiPointArithmeticPolicy);
this.randomGenerator = _randomGenerator;
this.multiPointArithmeticPolicy = _multiPointArithmeticPolicy;
}
@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(IntChromosome.class, chromosome1);
Validate.isInstanceOf(IntChromosome.class, chromosome2);
Validate.isTrue(chromosome1.getNumAlleles() == chromosome2.getNumAlleles());
Validate.isTrue(multiPointArithmeticPolicy.numCrossovers() < chromosome1.getNumAlleles());
Validate.isTrue(multiPointArithmeticPolicy.numCrossovers() < chromosome2.getNumAlleles());
final int numCrossovers = multiPointArithmeticPolicy.numCrossovers();
final double alpha = multiPointArithmeticPolicy.alpha();
final int[] alleleSplits = randomGenerator.ints(0, chromosome1.getNumAlleles())
.distinct()
.limit(numCrossovers)
.sorted()
.toArray();
final IntChromosome intChromosome1 = (IntChromosome) chromosome1;
final IntChromosome intChromosome2 = (IntChromosome) chromosome2;
final int numAlleles = chromosome1.getNumAlleles();
final int[] firstChildValues = new int[numAlleles];
final int[] secondChildValues = new int[numAlleles];
boolean useChromosome1 = true;
int splitIndex = 0;
for (int i = 0; i < intChromosome1.getNumAlleles(); i++) {
if (splitIndex < alleleSplits.length && i == alleleSplits[splitIndex]) {
splitIndex++;
useChromosome1 = !useChromosome1;
}
final int firstAllele = intChromosome1.getAllele(i);
final int secondAllele = intChromosome2.getAllele(i);
if (useChromosome1) {
firstChildValues[i] = (int) (alpha * firstAllele + (1 - alpha) * secondAllele);
secondChildValues[i] = (int) ((1 - alpha) * firstAllele + alpha * secondAllele);
} else {
firstChildValues[i] = (int) ((1 - alpha) * firstAllele + alpha * secondAllele);
secondChildValues[i] = (int) (alpha * firstAllele + (1 - alpha) * secondAllele);
}
}
return List.of(
new IntChromosome(numAlleles, intChromosome1.getMinValue(), intChromosome2.getMaxValue(), firstChildValues),
new IntChromosome(numAlleles,
intChromosome1.getMinValue(),
intChromosome2.getMaxValue(),
secondChildValues));
}
}