public void DoGeneration()
{
GenerationCount++;
// Create a list to hold our new offspring
var offspring = new List <Individual>();
// While our offspring are less than our current population count, create new offspring
while (offspring.Count < GAConfig.PopulationCount)
{
// Get parents
var mother = GetParent();
var father = GetParent();
// Handle the case where we have picked the same individual as both parents
while (mother == father)
{
father = GetParent();
}
// Perform Crossover
var(offspringA, offspringB) = GetOffspring(mother, father);
// Mutate
(offspringA, offspringB) = Mutate(offspringA, offspringB);
// Add offspring to population
offspring.Add(offspringA);
offspring.Add(offspringB);
}
// Add all the offspring to our existing population
Population.AddRange(offspring);
MultiObjectiveHelper.UpdatePopulationFitness(Population);
// Take the best 'PopulationCount' worth of individuals
var newPopulation = new List <Individual>();
foreach (var individual in Population.OrderBy(i => i.Rank).ThenByDescending(i => i.CrowdingDistance))
{
if (!newPopulation.Contains(individual))
{
newPopulation.Add(individual);
}
}
newPopulation = newPopulation.Take(GAConfig.PopulationCount).ToList();
Population.Clear();
newPopulation.ForEach(i => Population.Add(i));
}
public void EnsureRankTest()
{
var population = DefaultPopulationHelper.GetTestPopulation();
MultiObjectiveHelper.UpdatePopulationFitness(population);
Assert.AreEqual(population[0].Rank, 1);
Assert.AreEqual(population[1].Rank, 1);
Assert.AreEqual(population[2].Rank, 1);
Assert.AreEqual(population[3].Rank, 2);
Assert.AreEqual(population[4].Rank, 2);
Assert.AreEqual(population[5].Rank, 2);
Assert.AreEqual(population[6].Rank, 3);
}
public void EnsureCrowdingDistanceTest()
{
double epsilon = 0.00001;
var population = DefaultPopulationHelper.GetTestPopulation();
MultiObjectiveHelper.UpdatePopulationFitness(population);
Assert.IsTrue(double.IsPositiveInfinity(population[0].CrowdingDistance));
Assert.IsTrue(Math.Abs(population[1].CrowdingDistance - 0.9428089) < epsilon);
Assert.IsTrue(double.IsPositiveInfinity(population[2].CrowdingDistance));
Assert.IsTrue(double.IsPositiveInfinity(population[3].CrowdingDistance));
Assert.IsTrue(Math.Abs(population[4].CrowdingDistance - 0.9428089) < epsilon);
Assert.IsTrue(double.IsPositiveInfinity(population[5].CrowdingDistance));
Assert.IsTrue(double.IsPositiveInfinity(population[6].CrowdingDistance));
}
public void EnsureCrowdingDistanceTournamentSelectionTest()
{
var population = DefaultPopulationHelper.GetTestPopulation();
MultiObjectiveHelper.UpdatePopulationFitness(population);
// Rank 1, float.MaxValue crowding distance
var individualA = population[0];
// Rank 1, ~5.65 crowding distance
var individualB = population[1];
var fitterIndividualA = WorldHelper.TournamentSelection(individualA, individualB);
var fitterIndividualB = WorldHelper.TournamentSelection(individualB, individualA);
Assert.AreEqual(individualA, fitterIndividualA);
Assert.AreEqual(individualA, fitterIndividualB);
}
public void EnsureRankedTournamentSelectionTest()
{
var population = DefaultPopulationHelper.GetTestPopulation();
MultiObjectiveHelper.UpdatePopulationFitness(population);
// Rank 1
var individualA = population[1];
// Rank 2
var individualB = population[3];
var fitterIndividualA = WorldHelper.TournamentSelection(individualA, individualB);
var fitterIndividualB = WorldHelper.TournamentSelection(individualB, individualA);
Assert.AreEqual(individualA, fitterIndividualA);
Assert.AreEqual(individualA, fitterIndividualB);
}
