/// <summary>
/// Tell how different are 2 genomes. This is used in speciation.
/// </summary>
/// <returns>A normalized float.</returns>
public static float GeneticDistance(NEATConfig config, Genome genome1, Genome genome2)
{
var distance = 0f;
var comparisonInfo = new GenomeComparisonInfo(genome1, genome2);
var genesCountInBiggest = Mathf.Max(genome1.Genes.Count, genome2.Genes.Count);
var disjointDist = comparisonInfo.Disjoint.Count * config.speciesCompatibility.disjointImpact;
var excessDist = comparisonInfo.Excess.Count * config.speciesCompatibility.excessImpact;
distance += disjointDist / genesCountInBiggest;
distance += excessDist / genesCountInBiggest;
float totalWeightDif = 0;
foreach (var gene in comparisonInfo.Matching)
{
var weight1 = Mathf.Abs(genome1.GetGene(gene).Weight);
var weight2 = Mathf.Abs(genome2.GetGene(gene).Weight);
var diff = Mathf.Abs(weight1 - weight2) / Mathf.Max(weight1, weight2);
totalWeightDif += diff;
}
distance += totalWeightDif / comparisonInfo.Matching.Count * config.speciesCompatibility.weightMeanDifCoef;
distance /= config.speciesCompatibility.TotalImpactSum;
return(distance);
}
public GenomeComparisonInfo(Genome target1, Genome target2)
{
Target1 = target1;
Target2 = target2;
var genes1 = target1.Genes.OrderBy(x => x.InnovationNb).ToArray();
var genes2 = target2.Genes.OrderBy(x => x.InnovationNb).ToArray();
Disjoint = new Dictionary <Gene, Genome>();
Excess = new Dictionary <Gene, Genome>();
Matching = new List <Gene>();
var n = Mathf.Max(genes1.Length, genes2.Length);
var comparer = new GeneComparer();
for (int i = 0; i < n; i++)
{
if (i < genes1.Length)
{
var geneFromParent2 = target2.GetGene(genes1[i]);
if (geneFromParent2 != null)
{
if (Random.Range(0, 1f) <= 0.5f)
{
Matching.Add(genes1[i]);
}
else
{
Matching.Add(geneFromParent2);
}
}
else
{
if (genes2.Length != 0 && genes1[i].InnovationNb <= genes2.Last().InnovationNb)
{
Disjoint.Add(genes1[i], target1);
}
else
{
Excess.Add(genes1[i], target1);
}
}
}
if (i < genes2.Length && !genes1.Contains(genes2[i], comparer))
{
if (genes1.Length != 0 && genes2[i].InnovationNb <= genes1.Last().InnovationNb)
{
Disjoint.Add(genes2[i], target2);
}
else
{
Excess.Add(genes2[i], target2);
}
}
}
}