Crossover.cpp

#include "ECF_base.h"
 
const int RANDOM_GENOTYPE = 0;
const int ALL_GENOTYPES = 1;
 
 
void Crossover::registerParameters(StateP state)
{   
    state->getRegistry()->registerEntry("crossover.genotypes", (voidP) new std::string("random"), ECF::STRING,
        "if there are multiple genotypes, which to cross? 'random': a random pair, 'all': all pairs (default: random)");
    state->getRegistry()->registerEntry("crossover.protected", (voidP) new std::string(""), ECF::STRING,
        "indexes of genotypes (separated by spaces) that are excluded (protected) from crossover (default: none)");
}
 
 
bool Crossover::initialize(StateP state)
{
    state_ = state;
    protectedGenotypes_.clear();
    protectedGenotypes_.insert(protectedGenotypes_.begin(), operators.size(), false);
    opProb.clear();
 
    voidP sptr = state->getRegistry()->getEntry("crossover.genotypes");
    std::string crxGen = *((std::string*)sptr.get());
 
    crxGenotypes_ = RANDOM_GENOTYPE;
    if(crxGen == "all")
        crxGenotypes_ = ALL_GENOTYPES;
    else if(crxGen == "random")
        crxGenotypes_ = RANDOM_GENOTYPE;
    else
        ECF_LOG_ERROR(state, "Warning: invalid parameter value (key: crossover.genotypes)");
 
    // read protected genotypes
    std::stringstream ss;
    sptr = state->getRegistry()->getEntry("crossover.protected");
    ss << *((std::string*) sptr.get());
    uint genId;
    while(ss >> genId) {    // read all the data from string
        if(genId >= protectedGenotypes_.size()) {
            ECF_LOG_ERROR(state, "Error: invalid genotype index (key: crossover.protected)!");
            throw("");
        }
        protectedGenotypes_[genId] = true;
    }
 
    // initialize operators for all genotypes
    for(uint gen = 0; gen < operators.size(); gen++) {
        uint nOps = (uint) operators[gen].size();
        // if the genotype doesn't define crossover operators
        if(nOps == 0) {
            protectedGenotypes_[gen] = true;
            std::vector<double> empty;
            opProb.push_back(empty);
            break;
        }
        for(uint i = 0; i < nOps; i++) {
            operators[gen][i]->state_ = state;
            operators[gen][i]->initialize(state);
        }
        // calculate cumulative operator probabilities
        std::vector<double> probs(nOps);
        probs[0] = operators[gen][0]->probability_;
        for(uint i = 1; i < nOps; i++) {
            probs[i] = probs[i - 1] + operators[gen][i]->probability_;
        }
        if(probs[nOps - 1] == 0)
            probs[0] = -1;
        else
            if(probs[nOps - 1] != 1) {
                double normal = probs[nOps - 1];
                ECF_LOG_ERROR(state, "Warning: " + operators[gen][0]->myGenotype_->getName() +
                    " crossover operators: cumulative probability not equal to 1 (sum = " + dbl2str(normal) + ")");
                for(uint i = 0; i < probs.size(); i++)
                    probs[i] /= normal;
            }
        opProb.push_back(probs);
    }
    return true;
}
 
 
bool Crossover::mate(IndividualP ind1, IndividualP ind2, IndividualP child)
{
    child->fitness->setInvalid();
    // set crossover context
    state_->getContext()->firstParent = ind1;
    state_->getContext()->secondParent = ind2;
    state_->getContext()->child = child;
    ECF_LOG(state_, 5, "Crossover, 1st parent: " + ind1->toString() 
        + "\nCrossover, 2nd parent: " + ind2->toString());
 
    // check if any of the parents is also the child
    if(ind1 == child) {
        ind1 = (IndividualP) ind1->copy();
    }
    if(ind2 == child) {
        ind2 = (IndividualP) ind2->copy();
    }
 
    // TODO: parameter for genotype exchange (instead of genotype crossover)
 
    // default: choose radnom genotype pair to crx
    if(crxGenotypes_ == RANDOM_GENOTYPE) {
        uint iGenotype = state_->getRandomizer()->getRandomInteger((int)ind1->size());
        if(protectedGenotypes_[iGenotype])
            return false;
        // copy unchanged genotypes from parents
        for(uint i = 0; i < iGenotype; i++)
            child->at(i) = (GenotypeP) ind1->at(i)->copy();
        for(uint i = iGenotype + 1; i < child->size(); i++)
            child->at(i) = (GenotypeP) ind2->at(i)->copy();
        // choose operator
        uint iOperator;
        if(opProb[iGenotype][0] < 0)
            iOperator = state_->getRandomizer()->getRandomInteger((int)operators[iGenotype].size());
        else {
            double random = state_->getRandomizer()->getRandomDouble();
            iOperator = 0;
            while(opProb[iGenotype][iOperator] < random)
                iOperator++;
        }
        operators[iGenotype][iOperator]->mate(ind1->at(iGenotype), ind2->at(iGenotype), child->at(iGenotype));
    }
    // otherwise: crx all genotypes
    else if(crxGenotypes_ == ALL_GENOTYPES) {
        for(uint iGenotype = 0; iGenotype < ind1->size(); iGenotype++) {
            if(protectedGenotypes_[iGenotype])
                continue;
            // choose operator
            uint iOperator;
            if(opProb[iGenotype][0] < 0)
                iOperator = state_->getRandomizer()->getRandomInteger((int)operators[iGenotype].size());
            else {
                double random = state_->getRandomizer()->getRandomDouble();
                iOperator = 0;
                while(opProb[iGenotype][iOperator] < random)
                    iOperator++;
            }
            operators[iGenotype][iOperator]->mate(ind1->at(iGenotype), ind2->at(iGenotype), child->at(iGenotype));
        }
    }
 
    ECF_LOG(state_, 5, "Crossover, new individual: " + child->toString());
 
    return true;
}