eomggreplacement.h

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

   -----------------------------------------------------------------------------
   eoMGGReplacement.h 
   (c) Maarten Keijzer, Marc Schoenauer, 2002
 
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Contact: [e-mail]
             [e-mail]
 */
//-----------------------------------------------------------------------------

#ifndef _eoMGGReplacement_h
#define _eoMGGReplacement_h


//-----------------------------------------------------------------------------
#include <eoPop.h>
#include <eoFunctor.h>
#include <eoMerge.h>
#include <eoReduce.h>
#include <utils/eoHowMany.h>
#include <eoReduceSplit.h>
//-----------------------------------------------------------------------------

/**
eoMGGReplacement is an eoReplacement:
- choose N (2) parents RANDOMLY - remove them from the parent population
- select best offspring, add to parents
- merge (other?) offspring and the N removed parents
- select best N-1 of this merged population (detTournament only at the moment)
- put them back into parent population

*/

template <class EOT>
class eoMGGReplacement : public eoReplacement<EOT>
{
public:
  eoMGGReplacement(eoHowMany _howManyEliminatedParents = eoHowMany(2, false),
		   unsigned _tSize=2) :
    // split truncates the parents and returns eliminated parents
    split(_howManyEliminatedParents, true), 
    tSize(_tSize)
  {
    if (tSize < 2)
      { 
	std::cout << "Warning, Size for eoDetTournamentTruncateSplit adjusted to 2\n";
	tSize = 2;
      }
  }
    
    void operator()(eoPop<EOT> & _parents, eoPop<EOT> & _offspring)
    {
      eoPop<EOT> temp;
      split(_parents, temp);
      unsigned toKeep = temp.size(); // how many to keep from merged populations
      // minimal check
      if (toKeep < 2)
	throw std::runtime_error("Not enough parents killed in eoMGGReplacement");

      // select best offspring
      typename eoPop<EOT>::iterator it = _offspring.it_best_element();
      // add to parents
      _parents.push_back(*it);
      // remove from offspring
      _offspring.erase(it);

      // merge temp into offspring
      plus(temp, _offspring);
      
      // repeatedly add selected offspring to parents
      for (unsigned i=0; i<toKeep-1; i++)
	{
	  // select
	  it = deterministic_tournament(_offspring.begin(), _offspring.end(), tSize);
	  // add to parents
	  _parents.push_back(*it);
	  // remove from offspring
	  _offspring.erase(it);
	}
    }

private:
  eoLinearTruncateSplit<EOT> split; // few parents to truncate -> linear 
  eoPlus<EOT> plus;
  unsigned int tSize;
};

#endif