DoubleChromosomeCreepMutationHandler.java
package net.bmahe.genetics4j.core.mutation.chromosome.creepmutation;
import java.util.Arrays;
import java.util.function.Supplier;
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.mutation.chromosome.ChromosomeMutationHandler;
import net.bmahe.genetics4j.core.spec.chromosome.ChromosomeSpec;
import net.bmahe.genetics4j.core.spec.chromosome.DoubleChromosomeSpec;
import net.bmahe.genetics4j.core.spec.mutation.CreepMutation;
import net.bmahe.genetics4j.core.spec.mutation.MutationPolicy;
import net.bmahe.genetics4j.core.spec.statistics.distributions.Distribution;
import net.bmahe.genetics4j.core.util.DistributionUtils;
public class DoubleChromosomeCreepMutationHandler implements ChromosomeMutationHandler<DoubleChromosome> {
private final RandomGenerator randomGenerator;
public DoubleChromosomeCreepMutationHandler(final RandomGenerator _randomGenerator) {
Validate.notNull(_randomGenerator);
this.randomGenerator = _randomGenerator;
}
@Override
public boolean canHandle(final MutationPolicy mutationPolicy, final ChromosomeSpec chromosome) {
Validate.notNull(mutationPolicy);
Validate.notNull(chromosome);
return mutationPolicy instanceof CreepMutation && chromosome instanceof DoubleChromosomeSpec;
}
@Override
public DoubleChromosome mutate(final MutationPolicy mutationPolicy, final Chromosome chromosome) {
Validate.notNull(mutationPolicy);
Validate.notNull(chromosome);
Validate.isInstanceOf(CreepMutation.class, mutationPolicy);
Validate.isInstanceOf(DoubleChromosome.class, chromosome);
final var doubleChromosome = (DoubleChromosome) chromosome;
final var creepMutation = (CreepMutation) mutationPolicy;
final var minValue = doubleChromosome.getMinValue();
final var maxValue = doubleChromosome.getMaxValue();
final Distribution distribution = creepMutation.distribution();
final Supplier<Double> distributionValueSupplier = DistributionUtils
.distributionValueSupplier(randomGenerator, minValue, maxValue, distribution);
final double[] newValues = Arrays.copyOf(doubleChromosome.getValues(), doubleChromosome.getNumAlleles());
final int alleleFlipIndex = randomGenerator.nextInt(doubleChromosome.getNumAlleles());
newValues[alleleFlipIndex] += distributionValueSupplier.get();
if (newValues[alleleFlipIndex] > maxValue) {
newValues[alleleFlipIndex] = maxValue;
} else if (newValues[alleleFlipIndex] < minValue) {
newValues[alleleFlipIndex] = minValue;
}
return new DoubleChromosome(doubleChromosome.getSize(), doubleChromosome.getMinValue(),
doubleChromosome.getMaxValue(), newValues);
}
}