/** Assign the individual into a species, if not found, create a new one */
public void Speciate(IEvolutionState state, Individual ind)
{
NEATIndividual neatInd = (NEATIndividual)ind;
// For each individual, search for a subspecies it is compatible to
if (Subspecies.Count == 0) // not subspecies available, create the
// first species
{
NEATSubspecies newSubspecies = (NEATSubspecies)SubspeciesPrototype.EmptyClone();
newSubspecies.Reset();
Subspecies.Add(newSubspecies);
newSubspecies.AddNewGenIndividual(neatInd);
}
else
{
bool found = false;
foreach (NEATSubspecies s in Subspecies)
{
NEATIndividual represent = (NEATIndividual)s.NewGenerationFirst();
if (represent == null)
{
represent = (NEATIndividual)s.First();
}
// found compatible subspecies, add this individual to it
if (Compatibility(neatInd, represent) < CompatThreshold)
{
s.AddNewGenIndividual(neatInd);
found = true; // change flag
break; // search is over, quit loop
}
}
// if we didn't find a match, create a new subspecies
if (!found)
{
NEATSubspecies newSubspecies = (NEATSubspecies)SubspeciesPrototype.EmptyClone();
newSubspecies.Reset();
Subspecies.Add(newSubspecies);
newSubspecies.AddNewGenIndividual(neatInd);
}
}
}
/**
* Breed a new generation of population, this is done by first figure the
* expected offsprings for each subspecies, and then calls each subspecies
* to reproduce.
*/
public void BreedNewPopulation(IEvolutionState state, int subpop, int thread)
{
// see epoch method in Population
IList <Individual> inds = state.Population.Subpops[subpop].Individuals;
ClearEvaluationFlag(inds);
// clear the innovation information of last generation
Innovations.Clear();
// we also ignore the code for competitive coevolution stagnation
// detection
// Use Species' ages to modify the objective fitness of organisms
// in other words, make it more fair for younger species
// so they have a chance to take hold
// Also penalize stagnant species
// Then adjust the fitness using the species size to "share" fitness
// within a species.
// Then, within each Species, mark for death
// those below survivalThresh * average
foreach (NEATSubspecies s in Subspecies)
{
s.AdjustFitness(state, DropoffAge, AgeSignificance);
s.SortIndividuals();
s.UpdateSubspeciesMaxFitness();
s.MarkReproducableIndividuals(SurvivalThreshold);
}
// count the offspring for each subspecies
CountOffspring(state, subpop);
// sort the subspecies use extra list based on the max fitness
// these need to use original fitness, descending order
// BRS: Using LINQ instead of IComparer
IList <NEATSubspecies> sortedSubspecies = Subspecies
.OrderByDescending(s => s.Individuals[0].Fitness)
.ToList();
// Check for population-level stagnation code
PopulationStagnation(state, subpop, sortedSubspecies);
// Check for stagnation if there is stagnation, perform delta-coding
// TODO: fix weird constant
if (HighestLastChanged >= DropoffAge + 5)
{
DeltaCoding(state, subpop, sortedSubspecies);
}
// STOLEN BABIES: The system can take expected offspring away from
// worse species and give them to superior species depending on
// the system parameter babies_stolen (when babies_stolen > 0)
else if (BabiesStolen > 0)
{
StealBabies(state, thread, subpop, sortedSubspecies);
}
// Kill off all Individual marked for death. The remainder
// will be allowed to reproduce.
// NOTE this result the size change of individuals in each subspecies
// however, it doesn't effect the individuals for the whole neat
// population
foreach (NEATSubspecies s in sortedSubspecies)
{
s.RemovePoorFitnessIndividuals();
}
// Reproduction
// Perform reproduction. Reproduction is done on a per-Species
// basis. (So this could be paralellized potentially.)
// we do this with sortedSubspecies instead of subspecies
// this is due to the fact that new subspecies could be created during
// the reproduction period
// thus, the sortedSubspecies are guarantee to contain all the old
// subspecies
foreach (NEATSubspecies s in sortedSubspecies)
{
s.NewGenIndividuals.Clear();
}
foreach (NEATSubspecies s in sortedSubspecies)
{
s.Reproduce(state, thread, subpop, sortedSubspecies);
}
// Remove all empty subspecies and age ones that survive
// As this happens, create master individuals list for the new
// generation
// first age the old subspecies
foreach (NEATSubspecies s in sortedSubspecies)
{
s.Age++;
}
IList <NEATSubspecies> remainSubspecies = new List <NEATSubspecies>();
IList <Individual> newGenIndividuals = new List <Individual>();
foreach (NEATSubspecies s in Subspecies)
{
if (s.HasNewGeneration())
{
// add to the remaining subspecies
remainSubspecies.Add(s);
s.ToNewGeneration();
// add to the new generation population
((List <Individual>)newGenIndividuals).AddRange(s.Individuals);
}
}
// replace the old stuff
Subspecies = remainSubspecies;
state.Population.Subpops[subpop].Individuals = newGenIndividuals;
}
