roulettet.hpp

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/*
 *  Open BEAGLE
 *  Copyright (C) 2001-2005 by Christian Gagne and Marc Parizeau
 *
 *  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 2.1 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:
 *  Laboratoire de Vision et Systemes Numeriques
 *  Departement de genie electrique et de genie informatique
 *  Universite Laval, Quebec, Canada, G1K 7P4
 *  http://vision.gel.ulaval.ca
 *
 */

/*!
 *  \file   beagle/RouletteT.hpp
 *  \brief  Definition of class template RouletteT.
 *  \author Matthew Walker
 *  \author Christian Gagne
 *  $Revision: 1.8 $
 *  $Date: 2005/09/30 21:33:13 $
 */ 
 
#ifndef Beagle_RouletteT_hpp
#define Beagle_RouletteT_hpp

#include <vector>

#include "beagle/config.hpp"
#include "beagle/macros.hpp"
#include "beagle/Object.hpp"
#include "beagle/Randomizer.hpp"


namespace Beagle {

/*!
 *  \class RouletteT beagle/RouletteT.hpp "beagle/RouletteT.hpp"
 *  \brief Templated class defining a T-type roulette wheel.
 *  \param T Type of the values in the wheel.
 *  \ingroup OOF
 *  \ingroup Utils
 *  \author Matthew Walker
 *  \author Christian Gagne
 */
template <class T>
class RouletteT : public Beagle::Object,
                  public std::vector< std::pair<double,T>,BEAGLE_STLALLOCATOR< std::pair<double,T> > > {

public:

  typedef std::vector< std::pair<double,T>,BEAGLE_STLALLOCATOR< std::pair<double,T> > >
          VectorType;

  //! RouletteT allocator type.
  typedef AllocatorT<RouletteT<T>,Object::Alloc>
          Alloc;
  //! RouletteT handle type.
  typedef PointerT<RouletteT<T>,Object::Handle>
          Handle;
  //! RouletteT bag type.
  typedef ContainerT<RouletteT<T>,Object::Bag>
          Bag;

           RouletteT() { }
  virtual ~RouletteT() { }

  /*!
   *  \brief Insert a value into the roulette wheel.
   *  \param inValue The value to be inserted.
   *  \param inWeight The weighting to associate with the value.
   */
  inline void insert(const T& inValue, double inWeight=1.0)
  {
    Beagle_StackTraceBeginM();
    Beagle_AssertM(inWeight>=0.0);
    if(VectorType::empty()==false) inWeight += VectorType::back().first;
    push_back(std::make_pair(inWeight,inValue));
    Beagle_StackTraceEndM("void RouletteT<T>::insert(const T& inValue, double inWeight)");
  }

  /*!
   *  \brief Optimize distribution of values in the roulette.
   */
  inline void optimize()
  {
    Beagle_StackTraceBeginM();
    if(VectorType::size()<2) return;
    for(unsigned int i=(VectorType::size()-1); i>=1; --i) 
      (*this)[i].first -= (*this)[i-1].first;
    std::sort(VectorType::begin(), VectorType::end(), std::greater< std::pair<double,T> >());
    for(unsigned int i=1; i<VectorType::size(); ++i) 
      (*this)[i].first += (*this)[i-1].first;
    Beagle_StackTraceEndM("void RouletteT<T>::optimize()");
  }

  /*!
   *  \brief Select a value from the roulette wheel
   *  \param ioRandomizer Randomizer used to select element.
   */
  inline const T& select(Beagle::Randomizer& ioRandomizer) const
  {
    Beagle_StackTraceBeginM();
    Beagle_AssertM(VectorType::empty()==false);
    const double lDice = ioRandomizer.rollUniform(0.0, VectorType::back().first);
    unsigned int i;
    for(i=0; i<(VectorType::size()-1); ++i) if(lDice<(*this)[i].first) break;
    Beagle_AssertM(lDice<(*this)[i].first);
    return (*this)[i].second;
    Beagle_StackTraceEndM("const T& RouletteT<T>::select(Beagle::Randomizer& ioRandomizer) const");
  }

};

}


#endif // Beagle_RouletteT_hpp