public void UpdateBestIndividual()
{
// in ES, the best individual is the one with minimal fitness
double minFitness = double.PositiveInfinity;
int bestIndividualIndex = -1;
// iterate through all individuals
for (int index = 0; index < m_populationSize; index++)
{
double fitness = m_population[index].GetFitness();
if (fitness <= minFitness)
{
bestIndividualIndex = index;
minFitness = fitness;
}
}
// set the best individual base on bestIndividualIndex
if (bestIndividualIndex < 0)
{
throw new Exception("bestIndividualIndex is negative!");
}
else
{
m_bestIndividual = m_population[bestIndividualIndex];
}
}
public Chromesome(Chromesome parent)
{
world = parent.world;
data = new double[10];
stepSizes = new double[10];
parent.data.CopyTo(data, 0);
parent.stepSizes.CopyTo(stepSizes, 0);
singleStepSize = parent.singleStepSize;
}
public void ToNextGeneration()
{
m_currentGeneration++;
// (1,1) , always use children
if (!Configuration.s_isParentCandidate)
{
for (int index = 0; index < m_populationSize; index++)
{
double originalFitness = m_population[index].GetFitness();
m_population[index].Mutate();
double mutatedFitness = m_population[index].GetFitness();
}
}
else // (1+1)
{
for (int index = 0; index < m_populationSize; index++)
{
Chromesome parent = m_population[index];
Chromesome child = new Chromesome(parent);
// mutate the child
child.Mutate();
// in this case, parent wins
if (parent.GetFitness() < child.GetFitness())
{
m_population[index] = parent;
}
else // in this case, child (after mutation) wins
{
m_population[index] = child;
}
}
}
// set up for successful mutation
double originalBestFitness = BestIndividual.GetFitness();
// Update world status
UpdateBestIndividual();
double mutatedBestFitness = BestIndividual.GetFitness();
if (mutatedBestFitness < originalBestFitness)
{
m_successfulMutationCount++;
}
}
public World(int _populationSize, Func <World, bool> _terminateCondition)
{
// fixed initialization
m_currentGeneration = 0;
m_successfulMutationCount = 0;
// customed initialization
m_populationSize = _populationSize;
m_terminateCondition = _terminateCondition;
// initialization base on customed variables
m_population = new Chromesome[m_populationSize];
for (int index = 0; index < m_populationSize; index++)
{
m_population[index] = new Chromesome(this);
}
UpdateBestIndividual();
}
