moeoFrontByFrontCrowdingDiversityAssignment.h

/*
* <moeoFrontByFrontCrowdingDiversityAssignment.h>
* Copyright (C) DOLPHIN Project-Team, INRIA Futurs, 2006-2007
* (C) OPAC Team, LIFL, 2002-2007
*
* Arnaud Liefooghe
*
* This software is governed by the CeCILL license under French law and
* abiding by the rules of distribution of free software.  You can  use,
* modify and/ or redistribute the software under the terms of the CeCILL
* license as circulated by CEA, CNRS and INRIA at the following URL
* "http://www.cecill.info".
*
* As a counterpart to the access to the source code and  rights to copy,
* modify and redistribute granted by the license, users are provided only
* with a limited warranty  and the software's author,  the holder of the
* economic rights,  and the successive licensors  have only  limited liability.
*
* In this respect, the user's attention is drawn to the risks associated
* with loading,  using,  modifying and/or developing or reproducing the
* software by the user in light of its specific status of free software,
* that may mean  that it is complicated to manipulate,  and  that  also
* therefore means  that it is reserved for developers  and  experienced
* professionals having in-depth computer knowledge. Users are therefore
* encouraged to load and test the software's suitability as regards their
* requirements in conditions enabling the security of their systems and/or
* data to be ensured and,  more generally, to use and operate it in the
* same conditions as regards security.
* The fact that you are presently reading this means that you have had
* knowledge of the CeCILL license and that you accept its terms.
*
* ParadisEO WebSite : http://paradiseo.gforge.inria.fr
* Contact: paradiseo-help@lists.gforge.inria.fr
*
*/
//-----------------------------------------------------------------------------

#ifndef MOEOFRONTBYFRONTCROWDINGDIVERSITYASSIGNMENT_H_
#define MOEOFRONTBYFRONTCROWDINGDIVERSITYASSIGNMENT_H_

#include <diversity/moeoCrowdingDiversityAssignment.h>
#include <comparator/moeoFitnessThenDiversityComparator.h>

template < class MOEOT >
class moeoFrontByFrontCrowdingDiversityAssignment : public moeoCrowdingDiversityAssignment < MOEOT >
  {
  public:

    typedef typename MOEOT::ObjectiveVector ObjectiveVector;


    void updateByDeleting(eoPop < MOEOT > & _pop, ObjectiveVector & _objVec)
    {
      std::cout << "WARNING : updateByDeleting not implemented in moeoFrontByFrontCrowdingDistanceDiversityAssignment" << std::endl;
    }


  private:

    using moeoCrowdingDiversityAssignment < MOEOT >::inf;
    using moeoCrowdingDiversityAssignment < MOEOT >::tiny;

    void setDistances (eoPop < MOEOT > & _pop)
    {
      unsigned int a,b;
      double min, max, distance;
      unsigned int nObjectives = MOEOT::ObjectiveVector::nObjectives();
      // set diversity to 0 for every individual
      for (unsigned int i=0; i<_pop.size(); i++)
        {
          _pop[i].diversity(0.0);
        }
      // sort the whole pop according to fitness values
      moeoFitnessThenDiversityComparator < MOEOT > fitnessComparator;
      std::sort(_pop.begin(), _pop.end(), fitnessComparator);
      // compute the crowding distance values for every individual "front" by "front" (front : from a to b)
      a = 0;                                    // the front starts at a
      while (a < _pop.size())
        {
          b = lastIndex(_pop,a);        // the front ends at b
          // if there is less than 2 individuals in the front...
          if ((b-a) < 2)
            {
              for (unsigned int i=a; i<=b; i++)
                {
                  _pop[i].diversity(inf());
                }
            }
          // else...
          else
            {
              // for each objective
              for (unsigned int obj=0; obj<nObjectives; obj++)
                {
                  // sort in the descending order using the values of the objective 'obj'
                  moeoOneObjectiveComparator < MOEOT > objComp(obj);
                  std::sort(_pop.begin()+a, _pop.begin()+b+1, objComp);
                  // min & max
                  min = _pop[b].objectiveVector()[obj];
                  max = _pop[a].objectiveVector()[obj];
                  // avoid extreme case
                  if (min == max)
                    {
                      min -= tiny();
                      max += tiny();
                    }
                  // set the diversity value to infiny for min and max
                  _pop[a].diversity(inf());
                  _pop[b].diversity(inf());
                  // set the diversity values for the other individuals
                  for (unsigned int i=a+1; i<b; i++)
                    {
                      distance = (_pop[i-1].objectiveVector()[obj] - _pop[i+1].objectiveVector()[obj]) / (max-min);
                      _pop[i].diversity(_pop[i].diversity() + distance);
                    }
                }
            }
          // go to the next front
          a = b+1;
        }
    }


    unsigned int lastIndex (eoPop < MOEOT > & _pop, unsigned int _start)
    {
      unsigned int i=_start;
      while ( (i<_pop.size()-1) && (_pop[i].fitness()==_pop[i+1].fitness()) )
        {
          i++;
        }
      return i;
    }

  };

#endif /*MOEOFRONTBYFRONTCROWDINGDIVERSITYASSIGNMENT_H_*/

---