/// <summary>
/// Cross the specified parents generating the children.
/// </summary>
/// <param name="parents">The parents.</param>
/// <returns>The offspring (children) of the parents.</returns>
public override IList <IIndividual> Cross(IList <IIndividual> parents)
{
// This xover need same length
if (parents[0].Length != parents[1].Length)
{
return(parents);
}
// minimal parents lenght
if (parents[0].Length <= minParentSize)
{
return(parents);
}
// cross points
var crossPoints = RandomizationRnd.GetUniqueInts(2, 1, parents[0].Length - 2);
// new individuals
int firstIndex = crossPoints[0];
int secondIndex = crossPoints[1];
if (secondIndex < firstIndex)
{
secondIndex = crossPoints[0];
firstIndex = crossPoints[1];
}
var firstChild = CreateChild(parents[0], parents[1], firstIndex, secondIndex);
var secondChild = CreateChild(parents[1], parents[0], firstIndex, secondIndex);
return(new List <IIndividual>()
{
firstChild, secondChild
});
}
/// <summary>
/// Mutate the specified individual in population.
/// </summary>
/// <param name="individual">The individual to be mutated.</param>
/// <param name="mut_probability">The mutation probability to mutate each individual.</param>
public override void Mutate(IIndividual individual, float mutation_probabilty)
{
if (RandomizationRnd.GetDouble() <= mutation_probabilty)
{
var indexes = RandomizationRnd.GetUniqueInts(2, 0, individual.Length);
SwapGenes(indexes[0], indexes[1], individual);
}
}
/// <summary>
/// Selects the number of individuals from the generation.
/// </summary>
/// <param name="number">Number of selected.</param>
/// <param name="generation">Cur. generation</param>
/// <returns>Selected individuals.</returns>
public IList <IIndividual> SelectIndividuals(int number, IPopulation generation)
{
// previous generation
var candidates = generation.Individuals.ToList();
// new indiviudals
var selected = new List <IIndividual>();
// determine the winner by fitness
while (selected.Count < number)
{
var randomIndexes = RandomizationRnd.GetUniqueInts(2, 0, candidates.Count);
var tournamentWinner = candidates.Where((c, i) => randomIndexes.Contains(i)).OrderByDescending(c => c.Fitness).First();
selected.Add(tournamentWinner.Clone() as IIndividual);
}
return(selected);
}