ms.cpp

/*****************************************************************************
 *   Copyright (C) 2004-2015 The PaGMO development team,                     *
 *   Advanced Concepts Team (ACT), European Space Agency (ESA)               *
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 *   https://github.com/esa/pagmo                                            *
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 *   act@esa.int                                                             *
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#include <boost/random/uniform_int.hpp>
#include <boost/random/uniform_real.hpp>
#include <string>
#include <vector>

#include "../exceptions.h"
#include "../population.h"
#include "../problem/base.h"
#include "../types.h"
#include "base.h"
#include "ms.h"

namespace pagmo { namespace algorithm {


ms::ms(const base &algorithm, int starts):base(),m_starts(starts)
{
        m_algorithm = algorithm.clone();
        if (starts < 0) {
                pagmo_throw(value_error,"number of multistarts needs to be larger than zero");
        }
}

ms::ms(const ms &other):base(other),m_algorithm(other.m_algorithm->clone()),m_starts(other.m_starts) {}

base_ptr ms::clone() const
{
        return base_ptr(new ms(*this));
}


void ms::evolve(population &pop) const
{
        // Let's store some useful variables.
        const population::size_type NP = pop.size();

        // Get out if there is nothing to do.
        if (m_starts == 0 || NP == 0) {
                return;
        }

        // Local population used in the algorithm iterations.
        population working_pop(pop);

        //ms main loop
        for (int i=0; i< m_starts; ++i)
        {
                working_pop.reinit();
                m_algorithm->evolve(working_pop);
                if (working_pop.problem().compare_fc(working_pop.get_individual(working_pop.get_best_idx()).cur_f,working_pop.get_individual(working_pop.get_best_idx()).cur_c,
                        pop.get_individual(pop.get_worst_idx()).cur_f,pop.get_individual(pop.get_worst_idx()).cur_c
                ) )
                {
                        //update best population replacing its worst individual with the good one just produced.
                        pop.set_x(pop.get_worst_idx(),working_pop.get_individual(working_pop.get_best_idx()).cur_x);
                        pop.set_v(pop.get_worst_idx(),working_pop.get_individual(working_pop.get_best_idx()).cur_v);
                }
                if (m_screen_output)
                {
                        std::cout << i << ". " << "\tCurrent iteration best: " << working_pop.get_individual(working_pop.get_best_idx()).cur_f << "\tOverall champion: " << pop.champion().f << std::endl;
                }
        }
}


std::string ms::get_name() const
{
        return "Multi-start";
}


base_ptr ms::get_algorithm() const
{
        return m_algorithm->clone();
}


void ms::set_algorithm(const base &algo)
{
        m_algorithm = algo.clone();
}


std::string ms::human_readable_extra() const
{
        std::ostringstream s;
        s << "algorithm: " << m_algorithm->get_name() << ' ';
        s << "iter:" << m_starts << ' ';
        return s.str();
}

}} //namespaces

BOOST_CLASS_EXPORT_IMPLEMENT(pagmo::algorithm::ms)