spea2.h

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 *   Advanced Concepts Team (ACT), European Space Agency (ESA)               *
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#ifndef PAGMO_ALGORITHM_SPEA2_H
#define PAGMO_ALGORITHM_SPEA2_H

#include "../config.h"
#include "../serialization.h"
#include "../util/neighbourhood.h"
#include "base.h"

namespace pagmo { namespace algorithm {

class  distance_sorter {
public:
        distance_sorter(const std::vector<std::vector<pagmo::population::size_type>  > &neighbours,
                                        const std::vector<fitness_vector> &fit):
                m_neighbours(neighbours),
                m_fit(fit) {}
        bool operator()(unsigned int a, unsigned int b) {
                if(a>=m_fit.size() || a>=m_neighbours.size()){
                        pagmo_throw(value_error,"SPEA2 sorting of KNN values failure");
                }
                if(b>=m_fit.size() || b>=m_neighbours.size()){
                        pagmo_throw(value_error,"SPEA2 sorting of KNN values failure");
                }
                double delta_a, delta_b;
                unsigned int i = 0;
                do{
                        if(m_neighbours[b][i]>=m_fit.size() || m_neighbours[a][i]>=m_fit.size()){
                                pagmo_throw(value_error,"SPEA2 sorting of KNN values failure");
                        }
                        delta_a = pagmo::util::neighbourhood::euclidian::distance(m_fit[a], m_fit[m_neighbours[a][i]]);
                        delta_b = pagmo::util::neighbourhood::euclidian::distance(m_fit[b], m_fit[m_neighbours[b][i]]);
                        i++;
                } while (i<m_neighbours[0].size() && delta_a == delta_b);
                return delta_a > delta_b;
        }
private:
        const std::vector<std::vector<pagmo::population::size_type>  > &m_neighbours;
        const std::vector<fitness_vector> &m_fit;
};


class __PAGMO_VISIBLE spea2: public base
{
public:
        spea2(int gen=100, double cr = 0.95, double eta_c = 10, double m = 0.01, double eta_m = 50, int archive_size = 0);
        base_ptr clone() const;
        void evolve(population &) const;
        std::string get_name() const;

protected:
        std::string human_readable_extra() const;

private:
        struct spea2_individual {
                decision_vector x;
                fitness_vector f;
                constraint_vector c;
        };
        void compute_spea2_fitness(std::vector<double> &,
                                int K,
                                const std::vector<spea2_individual> &pop,
                                const pagmo::problem::base &prob) const;
        std::vector<std::vector<population::size_type> > compute_domination_list(const pagmo::problem::base &,
                                                                                                                                                        const std::vector<fitness_vector> &,
                                                                                                                                                        const std::vector<constraint_vector> &) const;
        std::vector<population::size_type> compute_pareto_rank(const std::vector<std::vector<population::size_type> > &) const;
        pagmo::population::size_type tournament_selection(pagmo::population::size_type, pagmo::population::size_type,
                                                                                                          const std::vector<population::size_type> &) const;
        std::vector<population::size_type> compute_domination_count(const std::vector<std::vector<population::size_type> > &) const;
        void crossover(decision_vector&, decision_vector&, pagmo::population::size_type, pagmo::population::size_type,
                                   const std::vector<spea2_individual> &, const pagmo::problem::base &) const;
        void mutate(decision_vector&, const pagmo::problem::base&) const;
        friend class boost::serialization::access;
        template <class Archive>
        void serialize(Archive &ar, const unsigned int)
        {
                ar & boost::serialization::base_object<base>(*this);
                ar & const_cast<int &>(m_gen);
                ar & const_cast<double &>(m_cr);
                ar & const_cast<double &>(m_eta_c);
                ar & const_cast<double &>(m_m);
                ar & const_cast<double &>(m_eta_m);
                ar & const_cast<int &>(m_archive_size);
        }
        //Number of generations
        const int m_gen;
        //Crossover rate
        const double m_cr;
        // Ditribution index for crossover
        const double m_eta_c;
        // Mutation rate
        const double m_m;
        // Ditribution index for mutation
        const double m_eta_m;
        // Size of the archive
        int m_archive_size;
};

}} //namespaces

BOOST_CLASS_EXPORT_KEY(pagmo::algorithm::spea2)

#endif // PAGMO_ALGORITHM_SPEA2_H