Added ranking selection (eoRankingSelect) and (linear) fitness scaling in

proportional selection (a completely different file, eoFitnessScalingSelect.h)

eo/src/eo

@@ -104,6 +104,8 @@
 #include <eoRandomSelect.h>
 #include <eoDetTournamentSelect.h>
 #include <eoProportionalSelect.h>
+#include <eoFitnessScalingSelect.h>
+#include <eoRankingSelect.h>
 #include <eoStochTournamentSelect.h>
 // the batch selection - from an eoSelectOne
 #include <eoSelectPerc.h>

eo/src/eoFitnessScalingSelect.h

@@ -0,0 +1,107 @@
+// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
+
+//-----------------------------------------------------------------------------
+// eoFitnessScalingSelect.h
+// (c) GeNeura Team, 1998, Maarten Keijzer 2000, 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: todos@geneura.ugr.es, http://geneura.ugr.es
+             Marc.Schoenauer@polytechnique.fr
+             mak@dhi.dk
+ */
+//-----------------------------------------------------------------------------
+
+#ifndef eoFitnessScalingSelect_h
+#define eoFitnessScalingSelect_h
+
+//-----------------------------------------------------------------------------
+
+#include <utils/eoRNG.h>
+#include <utils/selectors.h>
+#include <eoSelectOne.h>
+
+//-----------------------------------------------------------------------------
+/** eoFitnessScalingSelect: select an individual proportional to its rank
+          this is actually the linearRanking
+*/
+//-----------------------------------------------------------------------------
+
+template <class EOT> class eoFitnessScalingSelect: public eoSelectOne<EOT> 
+{
+public:
+     typedef typename EOT::Fitness Fitness;
+  /** Ctor:
+   *  @param _p the selective pressure, should be in [1,2] (2 is the default)
+   *  @param _pop an optional population
+   */
+  eoFitnessScalingSelect(double _p = 2.0, const eoPop<EOT>& _pop = eoPop<EOT>()): 
+    pressure(_p), scaledFitness(0) 
+  {
+    if (minimizing_fitness<EOT>())
+      throw logic_error("eoFitnessScalingSelect: minimizing fitness");
+    if (_pop.size() > 0)	   // a population in Ctor? initialize scaledFitness
+      {
+	setup(_pop);
+      }
+  }
+
+  // COmputes the coefficients of the linear transform in such a way that
+  // Pselect(Best) == pressure/sizePop
+  // Pselect(average) == 1.0/sizePop
+  // we truncate negative values to 0 - 
+  // we could also adjust the pressure so that worst get 0 scaled fitness
+  void setup(const eoPop<EOT>& _pop)
+  {
+    unsigned pSize =_pop.size();
+    scaledFitness.resize(pSize);
+
+    // best and worse fitnesses
+    double bestFitness = static_cast<double> (_pop.best_element().fitness());
+    double worstFitness = static_cast<double> (_pop.worse_element().fitness());
+
+    // average fitness
+    double sum=0.0;
+    for (unsigned i=0; i<pSize; i++)
+      sum += static_cast<double>(_pop[i].fitness());
+    double averageFitness = sum/pSize;
+
+    // the coefficients for linear scaling
+    double denom = pSize*(bestFitness - averageFitness);
+    double alpha = (pressure-1)/denom;
+    double beta = (bestFitness - pressure*averageFitness)/denom;
+//     if (beta < 0)
+//       beta = max(beta, -alpha*worstFitness);
+    for (unsigned i=0; i<pSize; i++) // truncate to 0
+      {
+	scaledFitness[i] = max(alpha*_pop[i].fitness()+beta, 0.0);
+      }
+  }
+    
+  /** do the selection, call roulette_wheel on rankFitness
+   */
+  const EOT& operator()(const eoPop<EOT>& _pop) 
+  {
+    unsigned selected = rng.roulette_wheel(scaledFitness);
+    return _pop[selected];
+  }
+
+private :
+  double pressure;
+  vector<double> scaledFitness;
+};
+
+#endif 
+

eo/src/eoRankingSelect.h

@@ -0,0 +1,90 @@
+// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
+
+//-----------------------------------------------------------------------------
+// eoRankingSelect.h
+// (c) GeNeura Team, 1998, Maarten Keijzer 2000, 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: todos@geneura.ugr.es, http://geneura.ugr.es
+             Marc.Schoenauer@polytechnique.fr
+             mak@dhi.dk
+ */
+//-----------------------------------------------------------------------------
+
+#ifndef eoRankingSelect_h
+#define eoRankingSelect_h
+
+//-----------------------------------------------------------------------------
+
+#include <utils/eoRNG.h>
+#include <utils/selectors.h>
+#include <eoSelectOne.h>
+
+//-----------------------------------------------------------------------------
+/** eoRankingSelect: select an individual proportional to its rank
+          this is actually the linearRanking
+*/
+//-----------------------------------------------------------------------------
+
+template <class EOT> class eoRankingSelect: public eoSelectOne<EOT> 
+{
+public:
+  /** Ctor:
+   *  @param _p the selective pressure, should be in [1,2] (2 is the default)
+   *  @param _pop an optional population
+   */
+  eoRankingSelect(double _p = 2.0, const eoPop<EOT>& _pop = eoPop<EOT>()): 
+    pressure(_p), rank(0), rankFitness(0) 
+  {
+    if (_pop.size() > 0)
+      {
+	setup(_pop);
+      }
+  }
+
+  // COmputes the coefficients of the linear transform uin such a way that
+  // Pselect(Best) == Pselect(sizePop) == pressure/sizePop
+  // Pselect(average) == 1.0/sizePop
+  // Pselect(Worst == Pselect(1 == (2-pressure)/sizePop
+  void setup(const eoPop<EOT>& _pop)
+  {
+    _pop.sort(rank);
+    unsigned pSize =_pop.size();
+    rankFitness.resize(pSize);
+    double alpha = (2*pressure-2)/(pSize*(pSize-1));
+    double beta = (2-pressure)/pSize;
+    for (unsigned i=0; i<pSize; i++)
+      {
+	rankFitness[i] = alpha*(pSize-1-i)+beta;
+      }
+  }
+    
+  /** do the selection, call roulette_wheel on rankFitness
+   */
+  const EOT& operator()(const eoPop<EOT>& _pop) 
+  {
+    unsigned selected = rng.roulette_wheel(rankFitness);
+    return *(rank[selected]);
+  }
+
+private :
+  double pressure;
+  vector<const EOT *> rank;
+  vector<double> rankFitness;
+};
+
+#endif 
+