SymbRegEvalOp.cpp

#include <cmath>
#include <ecf/ECF.h>
#include "SymbRegEvalOp.h"
 
 
// called only once, before the evolution – generates training data
bool SymbRegEvalOp::initialize(StateP state)
{
    nSamples = 10;
    double x = -10;
    for(uint i = 0; i < nSamples; i++) {
        domain.push_back(x);
        codomain.push_back(x + sin(x));
        x += 2;
    }
 
    return true;
}
 
 
FitnessP SymbRegEvalOp::evaluate(IndividualP individual)
{
    // we try to minimize the function value, so we use FitnessMin fitness (for minimization problems)
    FitnessP fitness (new FitnessMin);
 
    // get the genotype we defined in the configuration file
    Tree::Tree* tree = (Tree::Tree*) individual->getGenotype().get();
    // (you can also use boost smart pointers:)
    //TreeP tree = boost::static_pointer_cast<Tree::Tree> (individual->getGenotype());
 
    double value = 0;
    for(uint i = 0; i < nSamples; i++) {
        // for each test data instance, the x value (domain) must be set
        tree->setTerminalValue("X", &domain[i]);
        // get the y value of the current tree
        double result;
        tree->execute(&result);
        // add the difference
        value += fabs(codomain[i] - result);
    }
    fitness->setValue(value);
 
    return fitness;
}