1 package net.bmahe.genetics4j.core.mutation.chromosome.randommutation;
2
3 import java.util.BitSet;
4 import java.util.Objects;
5 import java.util.random.RandomGenerator;
6
7 import org.apache.commons.lang3.Validate;
8
9 import net.bmahe.genetics4j.core.chromosomes.BitChromosome;
10 import net.bmahe.genetics4j.core.chromosomes.Chromosome;
11 import net.bmahe.genetics4j.core.mutation.chromosome.ChromosomeMutationHandler;
12 import net.bmahe.genetics4j.core.spec.chromosome.BitChromosomeSpec;
13 import net.bmahe.genetics4j.core.spec.chromosome.ChromosomeSpec;
14 import net.bmahe.genetics4j.core.spec.mutation.MutationPolicy;
15 import net.bmahe.genetics4j.core.spec.mutation.RandomMutation;
16
17 public class BitChromosomeRandomMutationHandler implements ChromosomeMutationHandler<BitChromosome> {
18
19 private final RandomGenerator randomGenerator;
20
21 public BitChromosomeRandomMutationHandler(final RandomGenerator _randomGenerator) {
22 Objects.requireNonNull(_randomGenerator);
23
24 this.randomGenerator = _randomGenerator;
25 }
26
27 @Override
28 public boolean canHandle(final MutationPolicy mutationPolicy, final ChromosomeSpec chromosome) {
29 Objects.requireNonNull(mutationPolicy);
30 Objects.requireNonNull(chromosome);
31
32 return mutationPolicy instanceof RandomMutation && chromosome instanceof BitChromosomeSpec;
33 }
34
35 @Override
36 public BitChromosome mutate(final MutationPolicy mutationPolicy, final Chromosome chromosome) {
37 Objects.requireNonNull(mutationPolicy);
38 Objects.requireNonNull(chromosome);
39 Validate.isInstanceOf(RandomMutation.class, mutationPolicy);
40 Validate.isInstanceOf(BitChromosome.class, chromosome);
41
42 final BitChromosome bitChromosome = (BitChromosome) chromosome;
43
44 final BitSet newBitSet = new BitSet(bitChromosome.getNumAlleles());
45 for (int i = 0; i < bitChromosome.getNumAlleles(); i++) {
46 newBitSet.or(bitChromosome.getBitSet());
47 }
48
49 final int bitFlipIndex = randomGenerator.nextInt(bitChromosome.getNumAlleles());
50 newBitSet.flip(bitFlipIndex);
51
52 return new BitChromosome(bitChromosome.getNumAlleles(), newBitSet);
53 }
54 }