public Individual saveIndividual(int index, Individual indiv)
{
if(index < 0)
{
individuals[individuals.Length - 1] = indiv;
} else
{
individuals[index] = indiv;
}
return indiv;
}
// Calculate inidividuals fittness by comparing it to our candidate solution
public static double getFitness(Individual individual)
{
//fitness is just calculate de function
//------------------------------------
_exp.Parameters["x"] = individual.numericValue();
double result = double.Parse(_exp.Evaluate().ToString());
if(double.IsPositiveInfinity(result) || double.IsNegativeInfinity(result) || double.IsNaN(result)) {
return double.Epsilon;
} else {
return result;
}
}
public Population(int populationSize, bool initialise)
{
individuals = new Individual[populationSize];
if (initialise)
{
for (int i = 0; i<size();i++)
{
Individual newIndividual = new Individual();
newIndividual.generateIndividual();
saveIndividual(i, newIndividual);
}
}
}
public static double getProb(Individual individual)
{
if(individual.getFitness() != double.Epsilon) {
double prob = individual.getFitness() / _sumPopulationFitness;
if (_op == Operation.Max) {
return prob;
} else {
return (1 - prob);
}
} else {
return 0.0;
}
}
public static double getActualCount(Individual individual)
{
return Math.Round(getExpectedCount(individual));
}
public static double getExpectedCount(Individual individual)
{
double expectedCount = individual.getFitness() / _avgPopulationFitness;
return expectedCount;
}
private static bool betterFitness(Individual fittest, int i)
{
if (fittest.getFitness() != double.Epsilon) {
if (_op == Operation.Max) {
return fittest.getFitness() <= currentPopulation.getIndividual(i).getFitness();
} else {
return fittest.getFitness() >= currentPopulation.getIndividual(i).getFitness();
}
} else { return false; }
}
// Mutate an individual
private static void mutate(Individual indiv)
{
// Loop through genes
for (int i = 0; i < indiv.size(); i++) {
if (Rnd.NextDouble() <= MutationRate) {
// Create random gene
byte gene = (byte)Math.Round(Rnd.NextDouble());
indiv.setGene(i, gene);
}
}
}
// Crossover individuals
private static Individual crossover(Individual indiv1, Individual indiv2)
{
Individual newSol = new Individual();
// Loop through genes
for (int i = 0; i < indiv1.size(); i++) {
// Crossover
if (Rnd.NextDouble() <= UniformRate) {
newSol.setGene(i, indiv1.getGene(i));
} else {
newSol.setGene(i, indiv2.getGene(i));
}
}
return newSol;
}
//Evolve population
public static Population evolvePopulation(Population pop)
{
Population newPopulation = new Population(pop.size(), false);
Individual fittestOfThisPop = null;
//keep your best individual
if (Elitism) {
//get fittest of the CURRENT pop
fittestOfThisPop = newPopulation.saveIndividual(0, FitnessCalc.getFittest());
//SAVE best of the algorithm
if(bestSolution != null) {
if (betterFitness(bestSolution, fittestOfThisPop)) {
bestSolution = fittestOfThisPop;
}
} else {
bestSolution = fittestOfThisPop;
}
}
//Crossover population
int elitismOffset;
if (Elitism) {
elitismOffset = 1;
} else {
elitismOffset = 0;
}
//loop over tje population size and create new individuals with crossover
for(int i = elitismOffset; i<pop.size();i++) {
Individual indiv1 = rouletteSelection(pop);
Individual indiv2 = rouletteSelection(pop);
Individual newIndiv = crossover(indiv1, indiv2);
newPopulation.saveIndividual(i, newIndiv);
}
//Mutate population
for (int i=elitismOffset; i<newPopulation.size();i++) {
mutate(newPopulation.getIndividual(i));
}
// fitless die & replace by fittest
if (DieFactor) {
if (elitism) {
newPopulation.saveIndividual(FitnessCalc.getFitlessIndex(), fittestOfThisPop);
} else {
newPopulation.saveIndividual(FitnessCalc.getFitlessIndex(), FitnessCalc.getFittest());
}
}
return newPopulation;
}
public static bool betterFitness(Individual bestSol, Individual newBestSol)
{
if (bestSol.getFitness() != double.Epsilon) {
if (FitnessCalc._op == Operation.Max) {
return bestSol.getFitness() <= newBestSol.getFitness();
} else {
return bestSol.getFitness() >= newBestSol.getFitness();
}
} else { return false; }
}