StandardPropagation.cpp

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#include "StandardPropagation.h"
#include <algorithm>
#include <boost/numeric/ublas/matrix_proxy.hpp>
#include <boost/numeric/ublas/io.hpp>
#include <iostream>

using namespace std;
namespace ublas = boost::numeric::ublas;
namespace gplib
  {
    StandardPropagation::StandardPropagation(GeneralSelect* const LocalSelect,
        GeneralPopulation* const LocalPopulation, GeneralRNG* const LocalRandom) :
      GeneralPropagation(LocalSelect, LocalPopulation, LocalRandom)
      {
      }

    StandardPropagation::~StandardPropagation()
      {
      }

    void StandardPropagation::NextGeneration()
      {
        const int popsize = Population->GetPopulation().size1();
        const int genesize = Population->GetPopulation().size2();
        tpopulation NewPopulation(popsize, genesize);

        //first we initialize the selection object so that
        //it has the right probabilities etc.
        Select->Init();
        //we go through the whole population
        //because we go in pairs we have to treat the last elements specially
        for (int i = 0; i < popsize - 1; i += 2)
          {
            //select a "father" and a "mother" that will produce twins
            const int fatherindex = Select->GetOne();
            const int motherindex = Select->GetOne();
            //first take a local copy to work on
            tpopmember Son(ublas::row(Population->GetPopulation(), fatherindex));
            tpopmember Daughter(ublas::row(Population->GetPopulation(), motherindex));
            //then we do mutation and crossover
            Crossover(Son, Daughter);
            Mutation(Son);
            Mutation(Daughter);
            //then we assign to the new population
            ublas::row(NewPopulation, i) = Son;
            ublas::row(NewPopulation, i + 1) = Daughter;
          }
        //if we have an odd population sixze and therefore an extra member
        if ((popsize % 2) != 0)
          {
            //we just have a father that replicates and maybe mutates
            const int fatherindex = Select->GetOne();
            tpopmember Son(ublas::row(Population->GetPopulation(), fatherindex));
            Mutation(Son);
            ublas::row(NewPopulation, popsize - 1) = Son;
          }
        //The new population becomes the "main" population
        Population->SetPopulation(NewPopulation);
      }
  }