private Entity Tournament(Entity mate, int mateIndex)
{
// best fit
int position = -1;
double bestFitnes = double.PositiveInfinity;
// good enough fit still in current culture
int alrightPosition = -1;
double alrightFitness = double.PositiveInfinity;
for (int i = 0; i < Cfg.TournamentSize; ++i)
{
int index = R.NG.Next(Cfg.EntityCount);
while (index == mateIndex)
{
index = R.NG.Next(Cfg.EntityCount);
}
double compatibility = mate.Compatibility(Entities[index]);
if (Entities[index].Fitness <bestFitnes &&
compatibility> double.Epsilon && compatibility < 0.1) // if very compatible but not identical
{
bestFitnes = Entities[index].Fitness;
position = index;
}
else if (Entities[index].Fitness < alrightFitness && compatibility < 0.25) // if somewhat compatible or identical
{
alrightFitness = Entities[index].Fitness;
alrightPosition = index;
}
}
if (position == -1)
{
var targetCulture = parentIncubator.RandomCulture(this);
position = R.NG.Next(targetCulture.Entities.Count);
var entity = targetCulture.Entities[position];
if (alrightFitness < entity.ComputeFitness(Cfg.FitnessFunction))
{
return(Entities[alrightPosition]);
}
else
{
return(entity);
}
}
else
{
return(Entities[position]);
}
}
private int Prey(Entity hunter, int parentIndex)
{
if (hunter == null)
{
return(-1);
}
if (hunter.Fitness < Champion.Fitness) // if this dethrones the current champion
{
return(0);
}
int position = -1;
double worstFitness = hunter.Fitness;
for (int i = 0; i < Cfg.TournamentSize; ++i)
{
int index = R.NG.Next(Cfg.EntityCount);
while (index == parentIndex)
{
index = R.NG.Next(Cfg.EntityCount);
}
if (Entities[index].Fitness > hunter.Fitness &&
hunter.Compatibility(Entities[index]) < double.Epsilon) // if this is a better version of an existing structure
{
position = index;
break;
}
else if (Entities[index].Fitness > worstFitness)
{
worstFitness = Entities[index].Fitness;
position = index;
}
}
if (position == -1)
{
if (hunter.Fitness < Entities[parentIndex].Fitness ||
(Entities[parentIndex].ChildCount > 2 && parentIndex != 0))
{
position = parentIndex;
}
else
{
var targetCulture = parentIncubator.RandomCulture(this);
targetCulture.AttemptImigration(hunter);
}
}
return(position);
}
