eoparetofitness.h

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

//-----------------------------------------------------------------------------
// eoParetoFitness.h
// (c) Maarten Keijzer and Marc Schoenauer, 2001
/*
    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 _eoParetoFitness_h
#define _eoParetoFitness_h

#include <math.h>
#include <vector>
#include <stdexcept>
#include <iostream>


/**
 * eoFitnessTraits: a traits class to specify 
 *           the number of objectives and which one are maximizing or not
 * See test/t-eoParetoFitness for its use. 
 *
 * If you define your own, make sure you make the functions static!
*/
class eoParetoFitnessTraits
{
  public :

  static unsigned nObjectives()          { return 2; }
  static double tol()               { return 1e-6; }
  static bool maximizing(int which) { return true; } // by default: all are maximizing
};

/** 
 * eoVariableParetoTraits : an eoParetoFitnessTraits whose characteristics 
 *     can be set at run-time (nb objectives and min/max's)
 * Why bother? For didactical purposes (and EASEA implementation :-)
 */
class eoVariableParetoTraits : public eoParetoFitnessTraits
{
public :
  /** setting the static stuff */
  static void setUp(unsigned _n, std::vector<bool> & _b)
  {
    // possible problems
    if ( nObj && (nObj != _n) )	   // was already set to a different value
      {
	std::cout << "WARNING\n";
	std::cout << "WARNING : you are changing the number of objectives\n";
	std::cout << "WARNING : Make sure all existing objects are destroyed\n";
	std::cout << "WARNING\n";
      }
    nObj=_n; 
    bObj=_b;
    if (nObj != bObj.size())
      throw std::runtime_error("Number of objectives and min/max size don't match in VariableParetoTraits::setup");
  }

  /** the accessors */
  static unsigned nObjectives()
  { 
#ifndef NDEBUG
    if (!nObj)
      throw std::runtime_error("Number of objectives not assigned in VariableParetoTraits");
#endif
    return nObj; 
  }
  static bool maximizing(unsigned _i) 
  {
#ifndef NDEBUG
    if (_i >= bObj.size())
      throw std::runtime_error("Wrong index in VariableParetoTraits");
#endif
    return bObj[_i]; 
  }
private:
  static unsigned nObj;
  static std::vector<bool> bObj;
};

/**
  eoParetoFitness class: std::vector of doubles with overloaded comparison operators. Comparison is done
  on pareto dominance. The template argument FitnessTraits defaults to eoParetoFitnessTraits, which
  can be replaces at will by any other class that implements the static functions defined therein.

  Note that the comparison defines a partial order, so that
    !(a < b) && !(b <a) does not neccessarily imply that (a==b)
  The other way around does hold.
*/
template <class FitnessTraits = eoParetoFitnessTraits>
class eoParetoFitness : public std::vector<double>
{
public :

  typedef FitnessTraits fitness_traits;

  eoParetoFitness(void) : std::vector<double>(FitnessTraits::nObjectives(),0.0) {}

  // Ctr from a std::vector<double>
  eoParetoFitness(std::vector<double> & _v) : std::vector<double>(_v) {}
  

  /** access to the traits characteristics (so you don't have to write 
   * a lot of typedef's around
   */
  static void setUp(unsigned _n, std::vector<bool> & _b) {FitnessTraits::setUp(_n, _b);}
  static bool maximizing(unsigned _i) { return FitnessTraits::maximizing(_i);}

  /// Partial order based on Pareto-dominance
  //bool operator<(const eoParetoFitness<FitnessTraits>& _other) const
  bool dominates(const eoParetoFitness<FitnessTraits>& _other) const
  {
    bool dom = false;

    double tol = FitnessTraits::tol();
    const std::vector<double>& performance = *this;
    const std::vector<double>& otherperformance = _other;

    for (unsigned i = 0; i < FitnessTraits::nObjectives(); ++i)
    {
      bool maxim = FitnessTraits::maximizing(i);
      double aval = maxim? performance[i] : -performance[i];
      double bval = maxim? otherperformance[i] : -otherperformance[i];

      if (fabs(aval - bval) > tol)
      {
        if (aval < bval)
        {
          return false; // cannot dominate
        }
        // else aval < bval
        dom = true; // for the moment: goto next objective
      }
      //else they're equal in this objective, goto next
    }

    return dom;
  }

  /// compare *not* on dominance, but on the first, then the second, etc
  bool operator<(const eoParetoFitness<FitnessTraits>& _other) const
  {
    double tol = FitnessTraits::tol();
    const std::vector<double>& performance = *this;
    const std::vector<double>& otherperformance = _other;
    for (unsigned i = 0; i < FitnessTraits::nObjectives(); ++i)
    {
      bool maxim = FitnessTraits::maximizing(i);
      double aval = maxim? performance[i] : -performance[i];
      double bval = maxim? otherperformance[i] : -otherperformance[i];

      if (fabs(aval-bval) > tol)
      {
        if (aval < bval)
          return true;

        return false;
      }
    }

    return false;
  }

  bool operator>(const eoParetoFitness<FitnessTraits>& _other) const
  {
    return _other < *this;
  }

  bool operator<=(const eoParetoFitness<FitnessTraits>& _other) const
  {
    return operator==(_other) || operator<(_other);
  }

  bool operator>=(const eoParetoFitness<FitnessTraits>& _other) const
  {
    return _other <= *this;
  }

  bool operator==(const eoParetoFitness<FitnessTraits>& _other) const
  { // check if they're all within tolerance
    for (unsigned i = 0; i < size(); ++i)
    {
      if (fabs(operator[](i) - _other[i]) > FitnessTraits::tol())
      {
        return false;
      }
    }
    return true;
  }

  bool operator!=(const eoParetoFitness<FitnessTraits>& _other) const
  { return ! operator==(_other); }

};

template <class FitnessTraits>
std::ostream& operator<<(std::ostream& os, const eoParetoFitness<FitnessTraits>& fitness)
{
  for (unsigned i = 0; i < fitness.size(); ++i)
  {
    os << fitness[i] << ' ';
  }
  return os;
}

template <class FitnessTraits>
std::istream& operator>>(std::istream& is, eoParetoFitness<FitnessTraits>& fitness)
{
  fitness = eoParetoFitness<FitnessTraits>();
  for (unsigned i = 0; i < fitness.size(); ++i)
  {
    is >> fitness[i];
  }
  return is;
}

#endif