paradiseo/trunk/paradiseo-moeo/src/replacement/moeoEnvironmentalReplacement.h

// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-

//-----------------------------------------------------------------------------
// moeoEnvironmentalReplacement.h
// (c) OPAC Team (LIFL), Dolphin Project (INRIA), 2007
/*
    This library...

    Contact: paradiseo-help@lists.gforge.inria.fr, http://paradiseo.gforge.inria.fr
 */
//-----------------------------------------------------------------------------

#ifndef MOEOENVIRONMENTALREPLACEMENT_H_
#define MOEOENVIRONMENTALREPLACEMENT_H_

#include <comparator/moeoComparator.h>
#include <comparator/moeoFitnessThenDiversityComparator.h>
#include <diversity/moeoDiversityAssignment.h>
#include <fitness/moeoFitnessAssignment.h>
#include <replacement/moeoReplacement.h>

/**
 * Environmental replacement strategy that consists in keeping the N best individuals by deleting individuals 1 by 1
 * and by updating the fitness and diversity values after each deletion.
 */
template < class MOEOT > class moeoEnvironmentalReplacement:public moeoReplacement < MOEOT >
{
public:

    /** The type for objective vector */
    typedef typename MOEOT::ObjectiveVector ObjectiveVector;


    /**
     * Full constructor.
     * @param _fitnessAssignment the fitness assignment strategy
     * @param _diversityAssignment the diversity assignment strategy
     * @param _comparator the comparator (used to compare 2 individuals)
     */
    moeoEnvironmentalReplacement (moeoFitnessAssignment < MOEOT > & _fitnessAssignment, moeoDiversityAssignment < MOEOT > & _diversityAssignment, moeoComparator < MOEOT > & _comparator) :
            fitnessAssignment (_fitnessAssignment), diversityAssignment (_diversityAssignment), comparator (_comparator)
    {}


    /**
     * Constructor without comparator. A moeoFitThenDivComparator is used as default.
     * @param _fitnessAssignment the fitness assignment strategy
     * @param _diversityAssignment the diversity assignment strategy
     */
    moeoEnvironmentalReplacement (moeoFitnessAssignment < MOEOT > & _fitnessAssignment, moeoDiversityAssignment < MOEOT > & _diversityAssignment) :
            fitnessAssignment (_fitnessAssignment), diversityAssignment (_diversityAssignment), comparator (defaultComparator)
    {}


    /**
     * Constructor without moeoDiversityAssignement. A dummy diversity is used as default.
     * @param _fitnessAssignment the fitness assignment strategy
     * @param _comparator the comparator (used to compare 2 individuals)
     */
    moeoEnvironmentalReplacement (moeoFitnessAssignment < MOEOT > & _fitnessAssignment, moeoComparator < MOEOT > & _comparator) :
            fitnessAssignment (_fitnessAssignment), diversityAssignment (defaultDiversity), comparator (_comparator)
    {}


    /**
     * Constructor without moeoDiversityAssignement nor moeoComparator.
     * A moeoFitThenDivComparator and a dummy diversity are used as default.
     * @param _fitnessAssignment the fitness assignment strategy
     */
    moeoEnvironmentalReplacement (moeoFitnessAssignment < MOEOT > & _fitnessAssignment) :
            fitnessAssignment (_fitnessAssignment), diversityAssignment (defaultDiversity), comparator (defaultComparator)
    {}


    /**
     * Replaces the first population by adding the individuals of the second one, sorting with a moeoComparator and resizing the whole population obtained.
     * @param _parents the population composed of the parents (the population you want to replace)
     * @param _offspring the offspring population
     */
    void operator () (eoPop < MOEOT > &_parents, eoPop < MOEOT > &_offspring)
    {
        unsigned int sz = _parents.size();
        // merges offspring and parents into a global population
        _parents.reserve (_parents.size() + _offspring.size());
        std::copy (_offspring.begin(), _offspring.end(), back_inserter(_parents));
        // evaluates the fitness and the diversity of this global population
        fitnessAssignment (_parents);
        diversityAssignment (_parents);
        // remove individuals 1 by 1 and update the fitness values
        unsigned int worstIdx;
        ObjectiveVector worstObjVec;
        while (_parents.size() > sz)
        {
            // the individual to delete
            worstIdx = std::min_element(_parents.begin(), _parents.end(), comparator) - _parents.begin();
            worstObjVec = _parents[worstIdx].objectiveVector();
            // remove the woorst individual
            _parents[worstIdx] = _parents.back();
            _parents.pop_back();
            // update of the fitness and diversity values
            fitnessAssignment.updateByDeleting(_parents, worstObjVec);
            diversityAssignment.updateByDeleting(_parents, worstObjVec);

        }
        // clear the offspring population
        _offspring.clear ();
    }


protected:

    /** the fitness assignment strategy */
    moeoFitnessAssignment < MOEOT > & fitnessAssignment;
    /** the diversity assignment strategy */
    moeoDiversityAssignment < MOEOT > & diversityAssignment;
    /** a dummy diversity assignment can be used as default */
    moeoDummyDiversityAssignment < MOEOT > defaultDiversity;
    /** a fitness then diversity comparator can be used as default */
    moeoFitnessThenDiversityComparator < MOEOT > defaultComparator;
    /** this object is used to compare solutions in order to sort the population */
    class Cmp
    {
    public:
        /**
         * Ctor.
         * @param _comp the comparator
         */
        Cmp(moeoComparator < MOEOT > & _comp) : comp(_comp)
        {}
        /**
         * Returns true if _moeo1 is greater than _moeo2 according to the comparator
         * _moeo1 the first individual
         * _moeo2 the first individual
         */
        bool operator()(const MOEOT & _moeo1, const MOEOT & _moeo2)
        {
            return comp(_moeo1,_moeo2);
        }
    private:
        /** the comparator */
        moeoComparator < MOEOT > & comp;
    } comparator;

};

#endif /*MOEOENVIRONMENTALREPLACEMENT_H_ */