double Chromosome::create_random_gene(double const& gene_min,
double const& gene_max,
std::mt19937& urng) const
{
std::uniform_real_distribution<> uniform_distr(gene_min, gene_max);
return uniform_distr(urng);
}
double Particle_source::random_in_range(
const double low, const double up,
std::default_random_engine &rnd_gen )
{
std::uniform_real_distribution<double> uniform_distr( low, up );
return uniform_distr( rnd_gen );
}
int Generation::tournament_selection(std::mt19937& urng) const
{
std::uniform_int_distribution<int> uniform_distr(0, size-1);
int n1 = uniform_distr(urng);
int n2 = uniform_distr(urng);
if (chromosomes[n1].fitness < chromosomes[n2].fitness) return n1;
else return n2;
}
void Generation::mutate_chromosome(Chromosome& chromosome,
double const& prob_mutation,
std::vector<bound> const& param_bounds,
std::mt19937& urng) const
{
std::uniform_real_distribution<> uniform_distr(0.0, 1.0);
for (size_t i = 0; i < chromosome.size; ++i) {
if (uniform_distr(urng) <= prob_mutation) {
chromosome.genes[i] = chromosome.create_random_gene(param_bounds[i].lower, param_bounds[i].upper, urng);
}
}
}
void Generation::crossover_chromosomes(Chromosome& chromosome1, Chromosome& chromosome2,
double const& prob_crossover,
std::mt19937& urng) const
{
std::uniform_real_distribution<> uniform_distr(0.0, 1.0);
if (uniform_distr(urng) <= prob_crossover) {
std::vector<double> genes_temp; genes_temp.reserve(chromosome1.size); // store initial genes of the 1st chromosome
for (size_t i = 0; i < chromosome1.size; ++i) genes_temp.push_back(chromosome1.genes[i]);
std::uniform_int_distribution<int> uniform_distr2(1, chromosome1.size - 2);
int point = uniform_distr2(urng); // choose a random crossover point
for (int i = 0; i <= point; ++i) {
chromosome1.genes[i] = chromosome2.genes[i];
chromosome2.genes[i] = genes_temp[i];
}
}
}