IntChromosomeSwapMutationHandler.java
package net.bmahe.genetics4j.core.mutation.chromosome.swapmutation;
import java.util.Arrays;
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.mutation.chromosome.ChromosomeMutationHandler;
import net.bmahe.genetics4j.core.spec.chromosome.ChromosomeSpec;
import net.bmahe.genetics4j.core.spec.chromosome.IntChromosomeSpec;
import net.bmahe.genetics4j.core.spec.mutation.MutationPolicy;
import net.bmahe.genetics4j.core.spec.mutation.SwapMutation;
public class IntChromosomeSwapMutationHandler implements ChromosomeMutationHandler<IntChromosome> {
private final RandomGenerator randomGenerator;
public IntChromosomeSwapMutationHandler(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 SwapMutation && chromosome instanceof IntChromosomeSpec;
}
@Override
public IntChromosome mutate(final MutationPolicy mutationPolicy, final Chromosome chromosome) {
Validate.notNull(mutationPolicy);
Validate.notNull(chromosome);
Validate.isInstanceOf(SwapMutation.class, mutationPolicy);
Validate.isInstanceOf(IntChromosome.class, chromosome);
final SwapMutation swapMutation = (SwapMutation) mutationPolicy;
final int numSwap = swapMutation.isNumSwapFixed() ? swapMutation.numSwap()
: 1 + randomGenerator.nextInt(swapMutation.numSwap());
final IntChromosome intChromosome = (IntChromosome) chromosome;
final int[] values = intChromosome.getValues();
final int[] newValues = Arrays.copyOf(values, values.length);
for (int i = 0; i < numSwap; i++) {
final int value1Index = randomGenerator.nextInt(intChromosome.getNumAlleles());
final int value2Index = randomGenerator.nextInt(intChromosome.getNumAlleles());
final int value1 = newValues[value1Index];
final int value2 = newValues[value2Index];
newValues[value1Index] = value2;
newValues[value2Index] = value1;
}
final IntChromosome newIntChromosome = new IntChromosome(intChromosome.getSize(), intChromosome.getMinValue(),
intChromosome.getMaxValue(), newValues);
return newIntChromosome;
}
}