/// <summary>
/// Internal invocation the mutation operator.
/// </summary>
/// <param name="chromosome">The chromosome.</param>
/// <returns>The new DNA.</returns>
protected override IChromosome InternalInvoke(NeuralChromosome chromosome)
{
var innovationTracker = NeuralChromosome.GetInnovationTracker(chromosome.InnovationTrackerName);
var genes = chromosome.CloneGenes();
var nodeGenes = genes.Item1;
var edgeGenes = genes.Item2;
//No edge genes in the genotype yet. Return original chromosome.
if (edgeGenes.Count == 0)
{
return(new NeuralChromosome(nodeGenes, edgeGenes, chromosome.InnovationTrackerName,
chromosome.C1, chromosome.C2, chromosome.C3, chromosome.ActivationFunction));
}
var index = Session.Instance.Stochastic.Next(edgeGenes.Count);
var selectedEdge = edgeGenes[index];
var sourceNode = selectedEdge.Input;
var targetNode = selectedEdge.Output;
selectedEdge.Enabled = false;
var nodeId = innovationTracker.GetNextNodeInnovationNumber(selectedEdge.ID);
var newNode = new NeuralChromosome.NodeGene(nodeId, NeuralChromosome.NodeGene.NodeType.Hidden);
var edgeId1 = innovationTracker.GetNextEdgeInnovationNumber(sourceNode.ID, newNode.ID);
var newEdge1 = new NeuralChromosome.EdgeGene(edgeId1, selectedEdge.Input, newNode, 1, true);
var edgeId2 = innovationTracker.GetNextEdgeInnovationNumber(newNode.ID, targetNode.ID);
var newEdge2 = new NeuralChromosome.EdgeGene(edgeId2, newNode, selectedEdge.Output, selectedEdge.Weight, true);
nodeGenes.Add(newNode);
edgeGenes.Add(newEdge1);
edgeGenes.Add(newEdge2);
return(new NeuralChromosome(nodeGenes, edgeGenes, chromosome.InnovationTrackerName,
chromosome.C1, chromosome.C2, chromosome.C3, chromosome.ActivationFunction));
}
/// <summary>
/// Constructs an edge gene.
/// </summary>
/// <remarks>This constructor is for neural chromosomes.</remarks>
/// <param name="id">The edge gene id.</param>
/// <param name="input">The input node gene.</param>
/// <param name="output">The output node gene.</param>
/// <param name="weight">The edge genge weight.</param>
/// <param name="enabled">A value indicating if the edge gene is enabled.</param>
/// <returns></returns>
public static NeuralChromosome.EdgeGene ConstructEdgeGene(uint id,
NeuralChromosome.NodeGene input, NeuralChromosome.NodeGene output, double weight, bool enabled)
{
return(new NeuralChromosome.EdgeGene(id, input, output, weight, enabled));
}