/*
Returns i >= 0 where i is the index of the gene that it dislodged
itself to. i < 0 indicates it did not dislodge any gene.
*/
int try_dislodge(double *attempter, double *fitness, int age, int into_layer)
{
int i, k = into_layer;
if (k > MAX_LAYER) {
// Sorry. No layer above to dislodge oneself to.
return -1;
}
// start_search helps distribute the dislodge search evenly.
int start_search = rand() * POP_PER_LAYER;
for (i = 0; i < POP_PER_LAYER; i++) {
int li = (start_search + i) % POP_PER_LAYER;
int pi = INDIV_LINDEX(k, li);
double *fitness_b = fitness_matrix + FITNESS_LINDEX(k, li);
if (is_dominated(fitness, fitness_b)
|| ages[pi] > max_age[k]) {
// New genome dominates current one, or the current one is too old.
try_dislodge(genes[pi],
fitness_b,
ages[pi],
k + 1);
copy(attempter, genes[pi]);
memcpy(fitness_b, fitness, sizeof(double) * FITNESS_COUNT);
ages[pi] = age;
return pi;
}
}
return -2;
}
/* non_dominated_sorting: calculate fitness according to NSGA-II. Specially designed to consider only first Pareto front
* parameter: solutions matrix
* parameter: number of individuals
* returns: array with the Pareto front
*/
int* non_dominated_sorting(float ** solutions, int number_of_individuals)
{
/* iterators */
int iterator_solution = 0;
int iterator_comparision = 0;
/* Pareto front identificator initializated to 1 */
int solutions_allocated = 0;
/* Pareto fronts array */
int *pareto_fronts = (int *) malloc (number_of_individuals *sizeof (int));
/* Pareto fronts initializated to 0 */
for (iterator_solution=0; iterator_solution < number_of_individuals; iterator_solution++)
{
pareto_fronts[iterator_solution] = 0;
}
/* auxiliar integers */
int dominance;
int dont_add;
int allocated_solutions=0;
/* iterate on solutions */
for (iterator_solution=0; iterator_solution < number_of_individuals; iterator_solution++)
{
/* flag for a solution to be added */
dont_add = 0;
/* compare with the actual Pareto front */
if (pareto_fronts[iterator_solution]==0)
{
for (iterator_comparision=0; iterator_comparision < number_of_individuals; iterator_comparision++)
{
/* if the solution is not itself, it is not been evaluated or is in the actual Pareto front */
if (iterator_solution != iterator_comparision && pareto_fronts[iterator_comparision]==0 || pareto_fronts[iterator_comparision]==actual_pareto_front)
{
/* verificate the dominance between both*/
dominance = is_dominated(solutions,iterator_solution,iterator_comparision);
/* is dominated by a solution that is in the Pareto front, so this solution is not added*/
if (dominance == -1)
{
dont_add = 1;
break;
}
}
}
/* if the solution is not dominated by any other, let's add it to the actual Pareto front */
if (dont_add == 0)
{
pareto_fronts[iterator_solution] = actual_pareto_front;
}
}
}
return pareto_fronts;
}
