1 package net.bmahe.genetics4j.neat.mutation.chromosome;
2
3 import java.util.ArrayList;
4 import java.util.List;
5 import java.util.Objects;
6 import java.util.random.RandomGenerator;
7
8 import org.apache.commons.lang3.Validate;
9 import org.apache.logging.log4j.LogManager;
10 import org.apache.logging.log4j.Logger;
11
12 import net.bmahe.genetics4j.core.chromosomes.Chromosome;
13 import net.bmahe.genetics4j.core.mutation.chromosome.ChromosomeMutationHandler;
14 import net.bmahe.genetics4j.core.spec.chromosome.ChromosomeSpec;
15 import net.bmahe.genetics4j.core.spec.mutation.MutationPolicy;
16 import net.bmahe.genetics4j.neat.Connection;
17 import net.bmahe.genetics4j.neat.chromosomes.NeatChromosome;
18 import net.bmahe.genetics4j.neat.spec.NeatChromosomeSpec;
19 import net.bmahe.genetics4j.neat.spec.mutation.DeleteConnection;
20
21 public class NeatChromosomeDeleteConnection implements ChromosomeMutationHandler<NeatChromosome> {
22
23 public static final Logger logger = LogManager.getLogger(NeatChromosomeDeleteConnection.class);
24
25 private final RandomGenerator randomGenerator;
26
27 public NeatChromosomeDeleteConnection(final RandomGenerator _randomGenerator) {
28 Objects.requireNonNull(_randomGenerator);
29
30 this.randomGenerator = _randomGenerator;
31 }
32
33 @Override
34 public boolean canHandle(final MutationPolicy mutationPolicy, final ChromosomeSpec chromosome) {
35 Objects.requireNonNull(mutationPolicy);
36 Objects.requireNonNull(chromosome);
37
38 return mutationPolicy instanceof DeleteConnection && chromosome instanceof NeatChromosomeSpec;
39 }
40
41 @Override
42 public NeatChromosome mutate(final MutationPolicy mutationPolicy, final Chromosome chromosome) {
43 Objects.requireNonNull(mutationPolicy);
44 Objects.requireNonNull(chromosome);
45 Validate.isInstanceOf(DeleteConnection.class, mutationPolicy);
46 Validate.isInstanceOf(NeatChromosome.class, chromosome);
47
48 final var neatChromosome = (NeatChromosome) chromosome;
49 final var minValue = neatChromosome.getMinWeightValue();
50 final var maxValue = neatChromosome.getMaxWeightValue();
51
52 final var oldConnections = neatChromosome.getConnections();
53 final List<Connection> newConnections = new ArrayList<>(oldConnections);
54
55 if (oldConnections.isEmpty() == false) {
56 final int connectionToDeleteIndex = randomGenerator.nextInt(oldConnections.size());
57 newConnections.remove(connectionToDeleteIndex);
58 }
59
60 return new NeatChromosome(neatChromosome.getNodeLayout(), minValue, maxValue, newConnections);
61 }
62 }