/*! \file ScalingOperations.cpp
\brief This file contains implementation of scaling operations classes.
*/
/*
*
* website: http://www.coolsoft-sd.com/
* contact: support@coolsoft-sd.com
*
*/
/*
* Genetic Algorithm Library
* Copyright (C) 2007-2008 Coolsoft Software Development
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include "Population.h"
#include "ScalingOperations.h"
#include <math.h>
namespace Population
{
namespace ScalingOperations
{
// Scales chromosome fitness value based on passed parameters
float GaWindowScaling::operator ()(const GaScaledChromosome& chromosome,
const GaPopulation& population,
const GaScalingParams& parameters) const
{
float best = population.GetStatistics().GetValue( GSV_BEST_FITNESS_SCALED ).GetPrevious();
float worst = population.GetStatistics().GetValue( GSV_WORST_FITNESS_SCALED ).GetPrevious();
return chromosome.GetChromosome()->GetFitness() - ( best >= worst ? worst : best ) ;
}
// Returns TRUE if rescaling is needed for all chromosomes in population
bool GaWindowScaling::NeedRescaling(const GaPopulation& population,
const GaScalingParams& parameters) const
{
return population.GetStatistics().GetValue( GSV_WORST_FITNESS ).Changed();
}
// Scales chromosome fitness value based on passed parameters
float GaExponentialScaling::operator ()(const GaScaledChromosome& chromosome,
const GaPopulation& population,
const GaScalingParams& parameters) const
{
float factor = ( (const GaScaleFactorParams&) parameters ).GetFactor();
if( chromosome.GetChromosome()->GetFitness() == 0 && factor < 0 )
return 0;
return pow( chromosome.GetChromosome()->GetFitness(), factor );
}
// Returns TRUE if rescaling is needed for all chromosomes in population
bool GaExponentialScaling::NeedRescaling(const GaPopulation& population,
const GaScalingParams& parameters) const
{
GaScaledChromosome& c1 = population.GetAt( 0 );
if( c1.GetScaledFitness() != (*this)( c1, population, parameters ) )
return true;
GaScaledChromosome& c2 = population.GetAt( 0 );
if( c2.GetScaledFitness() != (*this)( c2, population, parameters ) )
return true;
return false;
}
// Scales chromosome fitness value based on passed parameters
float GaLinearScaling::operator ()(const GaScaledChromosome& chromosome,
const GaPopulation& population,
const GaScalingParams& parameters) const
{
float a, b, d;
float max = population.GetStatistics().GetValue( GSV_BEST_FITNESS ).GetPrevious();
float avg = population.GetStatistics().GetValue( GSV_AVG_FITNESS ).GetPrevious();
float min = population.GetStatistics().GetValue( GSV_WORST_FITNESS ).GetPrevious();
float f = ( (const GaScaleFactorParams&)parameters ).GetFactor();
if( min > ( f * avg - max ) / ( f - 1 ) )
{
d = max - avg;
if( fabs( d ) < 0.00001 )
a = 1, b = 0;
else
{
a = avg / d;
b = a * ( max - f * avg );
a *= ( f - 1 );
}
}
else
{
d = avg - min;
if( fabs( d ) < 0.00001 )
a = 1, b = 0;
else
{
a = avg / d;
b = -min * a;
}
}
return a * chromosome.GetChromosome()->GetFitness() + b;
}
// Returns TRUE if rescaling is needed for all chromosomes in population
bool GaLinearScaling::NeedRescaling(const GaPopulation& population,
const GaScalingParams& parameters) const
{
if( population.GetStatistics().GetValue( GSV_BEST_FITNESS ).Changed() )
return true;
if( population.GetStatistics().GetValue( GSV_AVG_FITNESS ).Changed() )
return true;
if( population.GetStatistics().GetValue( GSV_WORST_FITNESS ).Changed() )
return true;
GaScaledChromosome& c = population.GetAt( 0 );
return c.GetScaledFitness() != (*this)( c, population, parameters );
}
// Scales chromosome fitness value based on passed parameters
float GaNormalizationScaling::operator ()(const GaScaledChromosome& chromosome,
const GaPopulation& population,
const GaScalingParams& parameters) const
{
return (float)( population.GetCurrentSize() - chromosome.GetIndex() );
}
// Returns TRUE if rescaling is needed for all chromosomes in population
bool GaNormalizationScaling::NeedRescaling(const GaPopulation& population,
const GaScalingParams& parameters) const
{
return population.GetStatistics().GetValue( GSV_POPULATION_SIZE ).Changed();
}
} // ScalingOperations
} // Population