/// <summary>
/// Returns a mated child of the mother and father genome.
/// </summary>
/// <param name="mother">A parent Genome.</param>
/// <param name="father">A parent Genome.</param>
/// <param name="rando">A random number generator.</param>
/// <returns>A new genome based on the mating configuration.</returns>
public static Genome Mate(Genome mother, Genome father, Random rando)
{
MatingStyle style = ChooseMatingStyle(rando);
Genome child;
switch (style)
{
case MatingStyle.MultiPoint:
case MatingStyle.MultiPointAverage:
child = MateMultiPoint(style, mother, father, rando);
break;
case MatingStyle.SinglePoint:
child = MateSinglePoint(style, mother, father, rando);
break;
default:
throw new Exception("Mate function did not find a valid MatingStyle.");
}
return(child);
}
/// <summary>
/// Yarr... this be copied almost exactly as the original NEAT.
/// In the original NEAT, none of the settings had chance this would happen.
/// </summary>
/// <param name="style">The specific type of multi-point mating style.</param>
/// <param name="mother">A parent genome.</param>
/// <param name="father">A parent genome.</param>
/// <param name="rando">A random number generator.</param>
/// <returns>A product of the given multi-point mating style.</returns>
private static Genome MateSinglePoint(MatingStyle style, Genome mother, Genome father, Random rando)
{
mother.SortGenesByConnectionId();
father.SortGenesByConnectionId();
Genome largerParent = mother;
Genome smallerParent = father;
if (father.Size() > mother.Size())
{
largerParent = father;
smallerParent = mother;
}
List <Gene> childGenes = new List <Gene>();
int largerIndex = 0;
int smallerIndex = 0;
int crossoverPoint = rando.Next(smallerParent.Size());
int crossoverCounter = 0;
while (smallerParent.Size() != smallerIndex)
{
Gene chosenGene = new Gene();
if (largerIndex == largerParent.Size())
{
chosenGene.Copy(smallerParent.Genes[smallerIndex]);
smallerIndex++;
}
else if (smallerIndex == smallerParent.Size())
{
//Should never happen
chosenGene.Copy(largerParent.Genes[largerIndex]);
largerIndex++;
}
else
{
int largerGeneId = largerParent.Genes[largerIndex].Id;
int smallerGeneId = smallerParent.Genes[smallerIndex].Id;
if (largerGeneId == smallerGeneId)
{
if (crossoverCounter < crossoverPoint)
{
chosenGene.Copy(largerParent.Genes[largerIndex]);
}
else if (crossoverCounter > crossoverPoint)
{
chosenGene.Copy(smallerParent.Genes[smallerIndex]);
}
else
{
switch (style)
{
case MatingStyle.SinglePoint:
//Function is equivalent to what is needed here despite the misleading name.
MateMultiPointAverage(chosenGene, largerParent.Genes[largerIndex], smallerParent.Genes[smallerIndex], rando);
break;
default:
throw new Exception("MateSinglePoint was not given a valid mating style.");
}
}
chosenGene.Frozen = false;
//The NEAT implementation did not call for a chance this would happen. It just did it. [ NEAT.1.2.1 => Genome::mate_singlepoint(...) ]
if (largerParent.Genes[largerIndex].Frozen || smallerParent.Genes[smallerIndex].Frozen)
{
chosenGene.Frozen = true;
}
largerIndex++;
smallerIndex++;
crossoverCounter++;
}
else if (largerGeneId < smallerGeneId)
{
if (crossoverCounter < crossoverPoint)
{
chosenGene.Copy(largerParent.Genes[largerIndex]);
largerIndex++;
crossoverCounter++;
}
else
{
chosenGene.Copy(smallerParent.Genes[smallerIndex]);
smallerIndex++;
}
}
else
{
smallerIndex++;
continue;
}
}
if (GeneIsUnique(chosenGene, childGenes))
{
childGenes.Add(chosenGene);
}
}
return(new Genome(childGenes));
}
/// <summary>
/// Logic for disjoint/excess genes between mother/father in multi-point mating styles.
/// Delegates common genes to a more specific function.
/// </summary>
/// <param name="style">The specific type of multi-point mating style.</param>
/// <param name="mother">A parent genome.</param>
/// <param name="father">A parent genome.</param>
/// <param name="rando">A random number generator.</param>
/// <returns>A product of the given multi-point mating style.</returns>
private static Genome MateMultiPoint(MatingStyle style, Genome mother, Genome father, Random rando)
{
mother.SortGenesByConnectionId();
father.SortGenesByConnectionId();
Genome strongerParent = mother;
Genome weakerParent = father;
if (father.Fitness.Score > mother.Fitness.Score)
{
strongerParent = father;
weakerParent = mother;
}
List <Gene> childGenes = new List <Gene>();
int strongerIndex = 0;
int weakerIndex = 0;
while (strongerIndex < strongerParent.Size() || weakerIndex < weakerParent.Size())
{
Gene chosenGene = new Gene();
if (strongerIndex == strongerParent.Size())
{
break;
}
else if (weakerIndex == weakerParent.Size())
{
chosenGene.Copy(strongerParent.Genes[strongerIndex]);
strongerIndex++;
}
else
{
int strongerGeneId = strongerParent.Genes[strongerIndex].Id;
int weakerGeneId = weakerParent.Genes[weakerIndex].Id;
if (strongerGeneId == weakerGeneId)
{
switch (style)
{
case MatingStyle.MultiPoint:
MateMultiPointRegular(chosenGene, strongerParent.Genes[strongerIndex], weakerParent.Genes[weakerIndex], rando);
break;
case MatingStyle.MultiPointAverage:
MateMultiPointAverage(chosenGene, strongerParent.Genes[strongerIndex], weakerParent.Genes[weakerIndex], rando);
break;
default:
throw new Exception("MateMultiPoint was not given a valid mating style.");
}
//TODO: If both parents freeze their kid... should it be automatically frozen?
chosenGene.Frozen = false;
if (strongerParent.Genes[strongerIndex].Frozen && weakerParent.Genes[weakerIndex].Frozen)
{
chosenGene.Frozen = true;
}
else if (strongerParent.Genes[strongerIndex].Frozen || weakerParent.Genes[weakerIndex].Frozen)
{
if (rando.NextDouble() < FreezeGeneOfFrozenParentProbability)
{
chosenGene.Frozen = true;
}
}
strongerIndex++;
weakerIndex++;
}
else if (strongerGeneId < weakerGeneId)
{
chosenGene.Copy(strongerParent.Genes[strongerIndex]);
strongerIndex++;
}
else
{
weakerIndex++;
continue;
}
}
if (GeneIsUnique(chosenGene, childGenes))
{
childGenes.Add(chosenGene);
}
}
return(new Genome(childGenes));
}