/// <summary>
/// Approves a node gene for inclusion in the child chromosome.
/// </summary>
/// <param name="selected">The selected edge gene.</param>
/// <param name="approvedNodeGenes">The approved node genes.</param>
/// <param name="seen">The node gene seen tracker.</param>
private void ApproveNodeGenes(NeuralChromosome.EdgeGene selected,
ref List <NeuralChromosome.NodeGene> approvedNodeGenes, ref bool[] seen)
{
if (!seen[selected.Input.ID])
{
approvedNodeGenes.Add(selected.Input);
seen[selected.Input.ID] = true;
}
if (!seen[selected.Output.ID])
{
approvedNodeGenes.Add(selected.Output);
seen[selected.Output.ID] = true;
}
}
/// <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>
/// 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;
var sourceIndex = Session.Instance.Stochastic.Next(nodeGenes.Count);
var source = nodeGenes[sourceIndex];
var targetIndex = Session.Instance.Stochastic.Next(nodeGenes.Count);
var target = nodeGenes[targetIndex];
var index = targetIndex;
while (edgeGenes.Any(edge => edge.Input == source && edge.Output == target))
{
index = (index + 1) % nodeGenes.Count;
target = nodeGenes[index];
// Source node connects to all other nodes. Return original chromosome.
if (index == targetIndex)
{
return(new NeuralChromosome(nodeGenes, edgeGenes, chromosome.InnovationTrackerName,
chromosome.C1, chromosome.C2, chromosome.C3, chromosome.ActivationFunction));
}
}
var edgeId = innovationTracker.GetNextEdgeInnovationNumber(source.ID, target.ID);
var weight = Session.Instance.Stochastic.NextDouble();
var newEdge = new NeuralChromosome.EdgeGene(edgeId, source, target, weight, true);
edgeGenes.Add(newEdge);
return(new NeuralChromosome(nodeGenes, edgeGenes, chromosome.InnovationTrackerName,
chromosome.C1, chromosome.C2, chromosome.C3, chromosome.ActivationFunction));
}
