SymbRegEvalOp.cpp

#include "SymbRegEvalOp.h"
 
 
// called only once, before the evolution – generates training data
bool GEPSymbRegEvalOp::initialize(StateP state)
{
    x.clear();
    y.clear();
    f.clear();
    /*// check if the parameters are stated (used) in the conf. file
    // if not, we return false so the initialization fails
    if (!state->getRegistry()->isModified("x.data") || !state->getRegistry()->isModified("y.data") || !state->getRegistry()->isModified("f.data"))
            return false;
    // read from csv
    if(!csvRead(state,"x.data", &x)) return false;
    if(!csvRead(state,"y.data", &y)) return false;
    if(!csvRead(state,"f.data", &f)) return false;
    return true;
    */
    nSamples = 10;
    double s = .1;
    double X = -10*s;
    double Y = -10*s;
 
    for (uint i = 0; i < nSamples; i++) {
        x.push_back(X);
        y.push_back(Y);
        Y += 2*s;
        X += 2*s;
    }
 
    for (uint i = 0; i < nSamples; i++) {
        X = x.at(i);
        for (uint j = 0; j < nSamples; j++) {
            Y = y.at(j);
            // select target function
            //f.push_back(sin(X) + sin(Y*Y)); // F2
            //f.push_back(2*sin(X)*cos(Y)); // F3
            f.push_back(X*Y + sin((X + 1)*(Y - 1))); // F4
            //f.push_back(8 / (2+X*X+Y*Y)); // F5
            //f.push_back((X*X*X)/5+(Y*Y*Y)/2-X-Y); // F6
        }
    }
    return true;
}
 
bool GEPSymbRegEvalOp::csvRead(StateP state, std::string entry, std::vector<double>* vec){
    std::ifstream stream;
    std::string line;
    voidP sptr = state->getRegistry()->getEntry(entry);
    std::string fname = *((std::string*) sptr.get());
    stream.open(fname);
    if (!stream.is_open()) return false;
    while (getline(stream, line)){
        vec->push_back(atof(line.c_str()));
    }
    return true;
}
 
void GEPSymbRegEvalOp::registerParameters(StateP state)
{
    // optional - read data from input files
    /*
    state->getRegistry()->registerEntry("x.data", (voidP)(new std::string), ECF::STRING);
    state->getRegistry()->registerEntry("y.data", (voidP)(new std::string), ECF::STRING);
    state->getRegistry()->registerEntry("f.data", (voidP)(new std::string), ECF::STRING);
    */
}
 
FitnessP GEPSymbRegEvalOp::evaluate(IndividualP individual)
{
    // we try to minimize the function value, so we use FitnessMin fitness (for minimization problems)
    FitnessP fitness(new FitnessMin);
 
    // get genotype
    GEPChromosomeP gep = std::static_pointer_cast<GEP::GEPChromosome> (individual->getGenotype());
    // The system is multigenic. We iterate over every gene, transform it to a tree, execute it and link it with the results of its fellow genes
    // The user specifies the linking function programatically or in the parameters
 
    // a) just assemble the whole genotype in a single expression to evaluate
    gep->assemble();

    //std::vector<Tree::Tree*> tree;
    //tree.push_back(gep->makeCellTree());
    //for (uint g = 0; g < gep->genes; g++){
    //  tree.push_back(gep->toTree(g));
    //}
 
 
    double value = 0;
    double result;
    //nSamples = f.size();
    for(uint i = 0; i < nSamples; i++) {
        for (uint j = 0; j < nSamples; j++){
            result = 0;
 
            // a) execute the whole expression
            gep->setTerminalValue("X", &x.at(i));
            gep->setTerminalValue("Y", &y.at(j));
            gep->execute(&result);
 
            // b) or, execute every subtree and link manually
            /*
            for (uint g = 0; g < gep->genes; g++){
                // for each test data instance, the x value (domain) must be set
                tree.at(g)->setTerminalValue("X", &x.at(i));
                tree.at(g)->setTerminalValue("Y", &y.at(j));
 
                // get the f value of the current tree
                tree.at(g)->execute(&tmpResult);
                // link using addition (for example)
                result += tmpResult;
            }*/
 
            // add the difference
            value += pow(f.at(i*nSamples+j) - result, 2);
        }
    }
    value /= pow(nSamples,2);
    fitness->setValue(value);
    return fitness;
}