The perf2worth major check in

2 new important classes: eoPerf2Worth and eoSelectFromWorth
Instances of eoPerf2Worth are eoRanking and eoLinearFitScaling.
Coming soon (piece of cake now) are the niching strategies (sharing, clearing)

eo/src/eoLinearFitScaling.h

@@ -0,0 +1,90 @@
+/** -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
+
+   -----------------------------------------------------------------------------
+   eoLinearFitScaling.h 
+   (c) GeNeura Team, 1998, Maarten Keijzer, 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
+             Marc.Schoenauer@polytechnique.fr
+             mkeijzer@dhi.dk
+ */
+//-----------------------------------------------------------------------------
+
+#ifndef eoLinearFitScaling_h
+#define eoLinearFitScaling_h
+
+#include <eoSelectFromWorth.h>
+#include <eoPerf2Worth.h>
+
+/* An instance of eoPerf2Worth
+ *  COmputes the linearly scaled fitnesses
+ *  with given selective pressure
+ *  Pselect(Best) == pressure/sizePop
+ *  Pselect(average) == 1.0/sizePop
+ *  truncate negative values to 0 - 
+ *
+ * to be used within an eoSelectFromWorth object
+ */
+template <class EOT>
+class eoLinearFitScaling : public eoPerf2Worth<EOT>
+{
+public:
+  /* Ctor:
+   @param _p selective pressure (in (1,2]
+   @param _e exponent (1 == linear)
+  */
+  eoLinearFitScaling(double _p=2.0):
+    pressure(_p) {}
+
+  /* COmputes the ranked fitness: fitnesses range in [m,M] 
+     with m=2-pressure/popSize and M=pressure/popSize.
+     in between, the progression depends on exponent (linear if 1).
+   */
+  virtual void operator()(const eoPop<EOT>& _pop)
+    {
+      unsigned pSize =_pop.size();
+      // value() refers to the vector of worthes (we're in an eoParamvalue)
+      value().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;
+
+    for (unsigned i=0; i<pSize; i++) // truncate to 0
+      {
+	value()[i] = max(alpha*_pop[i].fitness()+beta, 0.0);
+      }
+
+    }
+ private:
+  double pressure;	// selective pressure
+};
+
+
+
+#endif