SelFitnessProportionalOp.cpp

#include "ECF_base.h"
#include "SelFitnessProportionalOp.h"
#include "SelBestOp.h"
#include "SelWorstOp.h"
#include <cmath>
 
 
bool SelFitnessProportionalOp::initialize(StateP state) {
    state_ = state;
    selPressure_ = 10;
    return true;
}
 
 
bool SelFitnessProportionalOp::setSelPressure(double selPressure)
{
    if(selPressure > 0){
        selPressure_ = selPressure;
        return true;
    }
    return false;
}
 
 
IndividualP SelFitnessProportionalOp::select(const std::vector<IndividualP>& pool)
{
    if(pool.empty())
        return IndividualP();
 
    SelBestOp best_;
    SelWorstOp worst_;
    IndividualP best = best_.select(pool);
    IndividualP worst = worst_.select(pool);
    double bestVal = best->fitness->getValue();
    double worstVal = worst->fitness->getValue();
    std::vector<double> howFit(pool.size(), 0.); 
 
    // check for uniform population
    if(fabs(bestVal - worstVal) < 0.000001)
        bestVal = worstVal + 1;
 
    howFit[0] = 1 + (selPressure_ - 1) * (pool[0]->fitness->getValue() - worstVal)/(bestVal - worstVal);
    for(uint i = 1; i<pool.size(); i++) {
        howFit[i] = 1 + (selPressure_ - 1) * (pool[i]->fitness->getValue() - worstVal)/(bestVal - worstVal);
        howFit[i] += howFit[i-1];
    }
 
    double randVal = state_->getRandomizer()->getRandomDouble() * howFit[howFit.size() - 1];
    uint chosen = 0;
    while(howFit[chosen] < randVal)
        chosen++;
 
    return pool[chosen];
}
 
 
std::vector<IndividualP> SelFitnessProportionalOp::selectMany(const std::vector<IndividualP>& pool, uint repeats)
{
    if(pool.empty())
        return pool;
 
    SelBestOp best_;
    SelWorstOp worst_;
    IndividualP best = best_.select(pool);
    IndividualP worst = worst_.select(pool);
    double bestVal = best->fitness->getValue();
    double worstVal = worst->fitness->getValue();
    std::vector<double> howFit(pool.size(), 0.);
    std::vector<IndividualP> selected;
 
    // check for uniform population
    if(fabs(bestVal - worstVal) < 0.000001)
        bestVal = worstVal + 1;
 
    howFit[0] = 1 + (selPressure_ - 1) * (pool[0]->fitness->getValue() - worstVal)/(bestVal - worstVal);
    for(uint i = 1; i<pool.size(); i++) {
        howFit[i] = 1 + (selPressure_ - 1) * (pool[i]->fitness->getValue() - worstVal)/(bestVal - worstVal);
        howFit[i] += howFit[i-1];
    }
 
    for(uint i = 0; i < repeats; i++) {
        double randVal = state_->getRandomizer()->getRandomDouble() * howFit[howFit.size() - 1];
        uint chosen = 0, begin = 0, end = (uint) howFit.size() - 1;
        while((begin + 1) < end) {
            chosen = (begin + end) / 2;
            if(howFit[chosen] > randVal)
                end = chosen;
            else
                begin = chosen;
        }
        if(howFit[begin] >= randVal)
            chosen = begin;
        else
            chosen = end;
 
//      while(howFit[chosen] < randVal)
//          chosen++;
        selected.push_back(pool[chosen]);
    }
 
    return selected;
}