private double computeFitness(Ind individual)
{
// -(Pow(x)) + 7x
var fitness = -(Math.Pow(individual.value(), 2)) + (7 * individual.value());
return(fitness);
}
/* Roulette selection */
private Func <Tuple <Ind, Ind> > selectTwoParents(Ind[] population, double[] fitnesses)
{
// Normalize the values
var lowestFitness = fitnesses.OrderBy(x => x).First();
var highestFitness = fitnesses.OrderBy(x => x).Last();
double[] normalizedFitnesses = new double[fitnesses.Length];
// All values are between 0-1
for (var i = 0; i < fitnesses.Length; i++)
{
normalizedFitnesses[i] = (fitnesses[i] - lowestFitness) / (highestFitness - lowestFitness);
}
var cumProbability = 0.0;
var totalProbability = normalizedFitnesses.Sum();
var avgNormalizedFitnesses = Enumerable.Range(0, populationSize).Select(i => normalizedFitnesses[i] / totalProbability).ToArray();
Ind parent1 = new Ind();
Ind parent2 = new Ind();
for (int i = 0; i < populationSize; i++)
{
cumProbability += normalizedFitnesses[i];
if (cumProbability >= r.NextDouble())
{
if (parent1.value() == 0)
{
parent1 = population[i];
}
else
{
parent2 = population[i];
break;
}
}
}
return(() => { return new Tuple <Ind, Ind>(parent1, parent2); });
}