1 package net.bmahe.genetics4j.neat.mutation.chromosome;
2
3 import java.util.ArrayList;
4 import java.util.Comparator;
5 import java.util.List;
6 import java.util.random.RandomGenerator;
7
8 import org.apache.commons.lang3.Validate;
9
10 import net.bmahe.genetics4j.neat.Connection;
11 import net.bmahe.genetics4j.neat.InnovationManager;
12 import net.bmahe.genetics4j.neat.chromosomes.NeatChromosome;
13 import net.bmahe.genetics4j.neat.spec.mutation.AddNode;
14
15 public class NeatChromosomeAddNodeMutationHandler extends AbstractNeatChromosomeConnectionMutationHandler<AddNode> {
16
17 private final RandomGenerator randomGenerator;
18 private final InnovationManager innovationManager;
19
20 public NeatChromosomeAddNodeMutationHandler(final RandomGenerator _randomGenerator,
21 final InnovationManager _innovationManager) {
22 super(AddNode.class, _randomGenerator);
23 Validate.notNull(_randomGenerator);
24 Validate.notNull(_innovationManager);
25
26 this.randomGenerator = _randomGenerator;
27 this.innovationManager = _innovationManager;
28 }
29
30 @Override
31 protected List<Connection> mutateConnection(final AddNode mutationPolicy, final NeatChromosome neatChromosome,
32 final Connection oldConnection, final int i) {
33
34 final List<Connection> connections = new ArrayList<>();
35
36 final var disabledConnection = Connection.builder().from(oldConnection).isEnabled(false).build();
37 connections.add(disabledConnection);
38
39 final int maxNodeConnectionsValue = neatChromosome.getConnections()
40 .stream()
41 .map(connection -> Math.max(connection.fromNodeIndex(), connection.toNodeIndex()))
42 .max(Comparator.naturalOrder())
43 .orElse(0);
44
45 final int maxNodeValue = Math
46 .max(maxNodeConnectionsValue, neatChromosome.getNumInputs() + neatChromosome.getNumOutputs() - 1);
47
48 final int newNodeValue = maxNodeValue + 1;
49
50 final int firstInnovation = innovationManager.computeNewId(oldConnection.fromNodeIndex(), newNodeValue);
51 final var firstConnection = Connection.builder()
52 .from(oldConnection)
53 .weight(1.0f)
54 .toNodeIndex(newNodeValue)
55 .innovation(firstInnovation)
56 .build();
57 connections.add(firstConnection);
58
59 final int secondInnovation = innovationManager.computeNewId(newNodeValue, oldConnection.toNodeIndex());
60 final var secondConnection = Connection.builder()
61 .from(oldConnection)
62 .fromNodeIndex(newNodeValue)
63 .innovation(secondInnovation)
64 .build();
65 connections.add(secondConnection);
66
67 return connections;
68 }
69
70 }