BitChromosomeSwapMutationHandler.java
package net.bmahe.genetics4j.core.mutation.chromosome.swapmutation;
import java.util.BitSet;
import java.util.random.RandomGenerator;
import org.apache.commons.lang3.Validate;
import net.bmahe.genetics4j.core.chromosomes.BitChromosome;
import net.bmahe.genetics4j.core.chromosomes.Chromosome;
import net.bmahe.genetics4j.core.mutation.chromosome.ChromosomeMutationHandler;
import net.bmahe.genetics4j.core.spec.chromosome.BitChromosomeSpec;
import net.bmahe.genetics4j.core.spec.chromosome.ChromosomeSpec;
import net.bmahe.genetics4j.core.spec.mutation.MutationPolicy;
import net.bmahe.genetics4j.core.spec.mutation.SwapMutation;
public class BitChromosomeSwapMutationHandler implements ChromosomeMutationHandler<BitChromosome> {
private final RandomGenerator randomGenerator;
public BitChromosomeSwapMutationHandler(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 BitChromosomeSpec;
}
@Override
public BitChromosome mutate(final MutationPolicy mutationPolicy, final Chromosome chromosome) {
Validate.notNull(mutationPolicy);
Validate.notNull(chromosome);
Validate.isInstanceOf(SwapMutation.class, mutationPolicy);
Validate.isInstanceOf(BitChromosome.class, chromosome);
final SwapMutation swapMutation = (SwapMutation) mutationPolicy;
final int numSwap = swapMutation.isNumSwapFixed() ? swapMutation.numSwap()
: 1 + randomGenerator.nextInt(swapMutation.numSwap());
final BitChromosome bitChromosome = (BitChromosome) chromosome;
final BitSet newBitSet = new BitSet(bitChromosome.getNumAlleles());
for (int i = 0; i < bitChromosome.getNumAlleles(); i++) {
newBitSet.or(bitChromosome.getBitSet());
}
for (int i = 0; i < numSwap; i++) {
final int value1Index = randomGenerator.nextInt(bitChromosome.getNumAlleles());
final int value2Index = randomGenerator.nextInt(bitChromosome.getNumAlleles());
final boolean value1 = newBitSet.get(value1Index);
final boolean value2 = newBitSet.get(value2Index);
newBitSet.set(value1Index, value2);
newBitSet.set(value2Index, value1);
}
final BitChromosome newBitChromosome = new BitChromosome(bitChromosome.getNumAlleles(), newBitSet);
return newBitChromosome;
}
}