94 lines
3.1 KiB
C++
94 lines
3.1 KiB
C++
/** -*- 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
|
|
*
|
|
* @ingroup Selectors
|
|
*/
|
|
template <class EOT>
|
|
class eoLinearFitScaling : public eoPerf2Worth<EOT> // false: do not cache fitness
|
|
{
|
|
public:
|
|
|
|
using eoPerf2Worth<EOT>::value;
|
|
|
|
/* 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;
|
|
unsigned i;
|
|
for (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 (i=0; i<pSize; i++) { // truncate to 0
|
|
value()[i] = std::max(alpha*_pop[i].fitness()+beta, 0.0);
|
|
}
|
|
}
|
|
|
|
private:
|
|
double pressure; // selective pressure
|
|
};
|
|
|
|
|
|
|
|
#endif
|