/// <summary>
/// Performs the elite operator.
/// This will copy the best chromosones from the current population to the next population
/// </summary>
/// <param name="currentPopulation">The current population.</param>
/// <param name="nextPopulation">The next population.</param>
public virtual void Process(Population currentPopulation, Population nextPopulation)
{
var amountToKeep = (int)(_elitePercentage * currentPopulation.Count);
for (var x = 0; x < amountToKeep; ++x)
{
nextPopulation.Add(currentPopulation[x].Clone());
}
}
/// <summary>
/// Creates a new population.
/// </summary>
/// <param name="population">The current population.</param>
/// <param name="elite">The elite operator.</param>
/// <param name="mutate">The mutate operator.</param>
/// <param name="crossover">The crossover operator.</param>
/// <param name="diversify">The diversify operator.</param>
/// <returns></returns>
public Population CreateNewPopulation(Population population, IElite elite, IMutate mutate, ICrossOver crossover, IDiversify diversify)
{
IChromosome parent1, parent2;
IChromosome child1 = null, child2 = null;
// create a new population
var nextPopulation = new Population();
// copy all elites to the new population
elite?.Process(population, nextPopulation);
// make sure the population is diversified enough
diversify?.Process(nextPopulation, population.Count);
// while next population is not filled completely
while (nextPopulation.Count < population.Count)
{
// select 2 parents
DoTournament(population, out parent1, out parent2);
// perform crossover so we get 2 children
crossover?.Process(parent1, parent2, out child1, out child2);
// mutate both children
mutate?.Process(child1);
mutate?.Process(child2);
// and add the children to the next population
nextPopulation.Add(child1);
if (nextPopulation.Count < population.Count)
{
nextPopulation.Add(child2);
}
}
return(nextPopulation);
}
/// <summary>
/// Adds new random chromosone to the next population to make sure the population is diversified enough.
/// </summary>
/// <param name="nextPopulation">The next population.</param>
/// <param name="populationSize">Size of the population.</param>
public void Process(Population nextPopulation, int populationSize)
{
var amount = (int)(populationSize * _replacePopulationPercentage);
for (var i = 0; i < amount; ++i)
{
var chromosome = CreateRandomChromosome();
if (chromosome != null)
{
nextPopulation.Add(chromosome);
}
if (nextPopulation.Count >= populationSize)
{
return;
}
}
}