neat_xor_fitness.hpp

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#pragma once
 
#include <array>
#include <vector>
 
#include "pulsatrix/neat_genome.hpp"
#include "pulsatrix/neat_phenotype.hpp"
 
namespace pulsatrix {
 
inline double XORFitness(const NEATGenome& genome) {
    static const std::array<std::array<double, 2>, 4> kInputs{
        {{0.0, 0.0}, {0.0, 1.0}, {1.0, 0.0}, {1.0, 1.0}}};
    static const std::array<double, 4> kExpected{0.0, 1.0, 1.0, 0.0};
 
    double sum_squared_error = 0.0;
    for (size_t i = 0; i < kInputs.size(); ++i) {
        std::vector<double> inputs(kInputs[i].begin(), kInputs[i].end());
        double actual = EvaluateNEATPhenotype(genome, inputs)[0];
        double error = kExpected[i] - actual;
        sum_squared_error += error * error;
    }
    return 4.0 - sum_squared_error;
}
 
}  // namespace pulsatrix