/// <summary>
/// Generates the next generation of the population.
/// </summary>
public void NextGeneration()
{
var avgDamage = Genomes.Average(g => g.DamageDealt);
var avgSurvivalTime = Genomes.Average(g => g.SurvivalTime);
// make a copy of the genomes and sort by fitness (high to low)
var orderedGenomes = Genomes.ToList();
orderedGenomes.Sort((a, b) =>
{
var aFitness = a.GetFitness(avgDamage, avgSurvivalTime);
var bFitness = b.GetFitness(avgDamage, avgSurvivalTime);
if (aFitness > bFitness)
{
return(1);
}
if (aFitness < bFitness)
{
return(-1);
}
return(0);
});
// trim out the worst genomes
var toRemove = (int)Math.Floor(ReplacementPercent * Size);
orderedGenomes.RemoveRange(Size - toRemove, toRemove);
for (var i = 0; i < Size; i++)
{
if (i < NumClones)
{
m_genomes[i] = orderedGenomes[i];
orderedGenomes[i].Id = i;
orderedGenomes[i].GenomeType = GenomeType.Clone;
orderedGenomes[i].ResetStats();
}
else
{
var genome = DoCrossover(orderedGenomes);
genome.Id = i;
if (Random.NextDouble() < MutationRate)
{
genome.Mutate();
}
m_genomes[i] = genome;
}
}
Generation++;
}
public void Evaluate(Func <IGenome, double> getFitness)
{
// Genome Fitness
Genomes.ForEach(g => g.Fitness = getFitness(g));
// Species Fitness
Species.ForEach(s => s.SetFitness());
// Population Fitness
Fitness = Genomes.Sum(g => g.Fitness);
AverageFitness = Genomes.Average(g => g.Fitness);
AverageFitness = AverageFitness == 0 ? 1 : AverageFitness;
// Genome Expected Offspring
Genomes.ForEach(g => g.ExpectedOffspring = g.Fitness / AverageFitness);
// Species Expected Offspring
Species.ForEach(s => s.SetExpectedOffspring());
}
public void SetFitness()
{
int ageDebt = (Age - LastImprovementAge + 1) - SpeciesParameters.DropOffAge;
ageDebt = ageDebt == 0 ? 1 : ageDebt;
Genomes.ForEach(g =>
{
if (ageDebt >= 1)
{
g.Fitness *= SpeciesParameters.DropOffAgePenaltyFactor;
}
if (Age <= 10)
{
g.Fitness *= SpeciesParameters.AgeSignificance;
}
if (g.Fitness < 0)
{
g.Fitness = 0.0001;
}
g.Fitness /= Genomes.Count;
});
Fitness = Genomes.Any() ? Genomes.Average(g => g.Fitness) : 0;
if (Fitness > MaxFitness)
{
MaxFitness = Fitness;
LastImprovementAge = 0;
}
else
{
LastImprovementAge++;
}
}