public static Population BreedPopulation(Population p, Evaluations e, getRandomGeneFunct getRandGene, double mutate_probability = MUTATION_RATE)
{
Population children = new Population();
DNAMateResult breed;
// Apply mate_at_random until enough children have been
// bred to match the size of the original population
while (children.Count != p.Count)
{
breed = Mate(p);
children.AddRange(breed);
}
return children;
}
public static Population Evolve(Population p, int generations, printPopulationFunct print, evaluateFunct evaluate, getRandomGeneFunct getRandGene, double mutation_rate = MUTATION_RATE)
{
Population c;
MutatedPopulation mutated;
Population children;
int gen = 0;
c = p;
while (gen < generations)
{
/*
* Rather than apply mutation while mating is occurring,
* we'll apply a population-wide possible mutation step before breeding commences.
* Each DNA string will have a chance of mutation. */
mutated = MutatePopulation(c, evaluate, getRandGene, mutation_rate);
children = BreedPopulation(mutated, mutated.evaluations, getRandGene, mutation_rate);
gen++;
if (print!= null) print(c, gen);
c = children;
}
return c;
}
public static Population Evolve(Population p, int generations, Evaluator evaluator, getRandomGeneFunct getRandGene, double mutation_rate = MUTATION_RATE)
{
return Evolve(p, generations, null, evaluator.eval, getRandGene, mutation_rate);
}
/// <summary>
/// Mutation Predicate.
/// Performs a mutation on chance.
/// Mutation occurs if calculated chance is less than required probability, otherwise the DNA is not affected.
/// </summary>
/// <param name="probability">
/// Probability of mutation occuring.
/// Value must be between 0.0 and 1.0
/// </param>
/// <returns>
/// Either a mutated DNA or unaffected DNA
/// </returns>
public static Mutant mutate_by_chance(DNA original, getRandomGeneFunct randomGene,
double probability = MUTATION_RATE)
{
Mutant m;
int mut_index; // a random point in the DNA at which mutation will occur
Random rand = new Random();
if (rand.NextDouble() < probability)
{
mut_index = rand.Next(1, original.Count);
return mutate(mut_index, original, randomGene);
}
else
{
m = new Mutant(original);
}
return m;
}
public static MutatedPopulation MutatePopulation(Population p, evaluateFunct evaluate, getRandomGeneFunct getRandGene, double mutate_probability = MUTATION_RATE)
{
MutatedPopulation mutated;
mutated = new MutatedPopulation(p.Select((child) =>
mutate_by_chance(child, getRandGene, mutate_probability)),null);
mutated.evaluations = mutated.RunFitnessTests(evaluate);
return mutated;
}
/// <summary>
/// Mutation Predicate.
/// Modifies a DNA string by changing one of its bases to be a random new value
/// </summary>
/// <param name="mut_index">
/// The point in which mutation is applied.
/// </param>
/// <param name="randomGene">
/// The function used to supply random Genes
/// </param>
public static Mutant mutate(int mut_index, DNA original, getRandomGeneFunct randomGene)
{
Mutant m;
DNA g_dna;
DNAPartial g_partial;
DNAPartial rest;
Gene g;
g=randomGene();
while (original.Contains(g))
g = randomGene();
g_dna = new DNA();
g_dna.Add(g);
var sp_mut = split(mut_index-1, original);
g_partial = split(0, g_dna).back;
// remove the base at the location that mutation is to occur
DNA back = join(new DNAPartial(), sp_mut.back);
back.RemoveAt(0);
// add mutated item
back = join(g_partial, split(0,back).back);
DNA front = join(new DNAPartial(), sp_mut.front);
// join front, mutation, and rest, lists together
rest = split(0, join(split(0,front).back, split(0, back).back)).back;
m = new Mutant(join(new DNAPartial(), rest));
return m;
}
