paradiseo/eo/src/moo/eoNSGA_II_Eval.cpp

81 lines
2.2 KiB
C++

#include <limits>
#include <eoNSGA_II_Eval.h>
namespace nsga2 {
using namespace std;
typedef std::pair<double, unsigned> double_index_pair;
class compare_nodes
{
public :
bool operator()(const double_index_pair& a, const double_index_pair& b) const
{
return a.first < b.first;
}
};
void assign_worths(const std::vector<detail::FitnessInfo>& front, unsigned rank, std::vector<double>& worths) {
unsigned nObjectives = front[0].fitness.size(); //traits::nObjectives(); //_pop[_cf[0]].fitness().size();
std::vector<double> niche_distance(front.size());
for (unsigned o = 0; o < nObjectives; ++o)
{
std::vector<std::pair<double, unsigned> > performance(front.size());
for (unsigned i =0; i < front.size(); ++i)
{
performance[i].first = front[i].fitness[o];
performance[i].second = i;
}
std::sort(performance.begin(), performance.end(), compare_nodes()); // a lambda operator would've been nice here
std::vector<double> nc(front.size(), 0.0);
for (unsigned i = 1; i < front.size()-1; ++i)
{ // and yet another level of indirection
nc[performance[i].second] = performance[i+1].first - performance[i-1].first;
}
// set boundary at max_dist + 1 (so it will get chosen over all the others
//nc[performance[0].second] += 0;
nc[performance.back().second] = std::numeric_limits<double>::infinity(); // best on objective
for (unsigned i = 0; i < nc.size(); ++i)
{
niche_distance[i] += nc[i];
}
}
// now we've got niche_distances, scale them between (0, 1), making sure that infinities get maximum rank
double max = 0;
for (unsigned i = 0; i < niche_distance.size(); ++i) {
if (niche_distance[i] != std::numeric_limits<double>::infinity()) {
max = std::max(max, niche_distance[i]);
}
}
for (unsigned i = 0; i < front.size(); ++i) {
double dist = niche_distance[i];
if (dist == std::numeric_limits<double>::infinity()) {
dist = 1.0;
} else {
dist /= (1+max);
}
unsigned idx = front[i].index;
worths[idx] = rank + dist;
}
}
}