paradiseo/trunk/paradiseo-moeo/src/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 <moeoReplacement.h>
#include <moeoComparator.h>
#include <moeoFitnessAssignment.h>
#include <moeoDiversityAssignment.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 _evalFitness the fitness assignment strategy
     * @param _evalDiversity the diversity assignment strategy
     * @param _comparator the comparator (used to compare 2 individuals)
     */
    moeoEnvironmentalReplacement (moeoFitnessAssignment < MOEOT > & _evalFitness, moeoDiversityAssignment < MOEOT > & _evalDiversity, moeoComparator < MOEOT > & _comparator) :
            evalFitness (_evalFitness), evalDiversity (_evalDiversity), comparator (_comparator)
    {}


    /**
     * Constructor without comparator. A moeoFitThenDivComparator is used as default.
     * @param _evalFitness the fitness assignment strategy
     * @param _evalDiversity the diversity assignment strategy
     */
    moeoEnvironmentalReplacement (moeoFitnessAssignment < MOEOT > & _evalFitness, moeoDiversityAssignment < MOEOT > & _evalDiversity) :
            evalFitness (_evalFitness), evalDiversity (_evalDiversity), comparator (*(new moeoFitnessThenDiversityComparator < MOEOT >))
    {}


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


    /**
     * Constructor without moeoDiversityAssignement nor moeoComparator.
     * A moeoFitThenDivComparator and a dummy diversity are used as default.
     * @param _evalFitness the fitness assignment strategy
     */
    moeoEnvironmentalReplacement (moeoFitnessAssignment < MOEOT > & _evalFitness) :
            evalFitness (_evalFitness), evalDiversity (*(new moeoDummyDiversityAssignment < MOEOT >)), comparator (*(new moeoFitnessThenDiversityComparator < MOEOT >))
    {}


    /**
     * 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 sz = _parents.size();
        // merges offspring and parents into a global population
        _parents.reserve (_parents.size() + _offspring.size());
        copy (_offspring.begin(), _offspring.end(), back_inserter(_parents));
        // evaluates the fitness and the diversity of this global population
        evalFitness (_parents);
        evalDiversity (_parents);
        // remove individuals 1 by 1 and update the fitness values
        Cmp cmp(comparator);
        ObjectiveVector worstObjVec;
        while (_parents.size() > sz)
        {
            std::sort (_parents.begin(), _parents.end(), cmp);
            worstObjVec = _parents[_parents.size()-1].objectiveVector();
            _parents.resize(_parents.size()-1);
            evalFitness.updateByDeleting(_parents, worstObjVec);
            evalDiversity.updateByDeleting(_parents, worstObjVec);
        }
        // clear the offspring population
        _offspring.clear ();
    }


protected:

    /** the fitness assignment strategy */
    moeoFitnessAssignment < MOEOT > & evalFitness;
    /** the diversity assignment strategy */
    moeoDiversityAssignment < MOEOT > & evalDiversity;
    /** the comparator (used to compare 2 individuals) */
    moeoComparator < MOEOT > & comparator;


    /**
     * This class is used to compare solutions in order to sort the population.
     */
    class Cmp
    {
    public:

        /**
         * Ctor.
         * @param _comparator the comparator
         */
        Cmp(moeoComparator < MOEOT > & _comparator) : comparator(_comparator)
        {}


        /**
         * 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 comparator(_moeo1,_moeo2);
        }


    private:

        /** the comparator */
        moeoComparator < MOEOT > & comparator;

    };

};

#endif /*MOEOENVIRONMENTALREPLACEMENT_H_ */