FitnessRepository.h

// Copyright QED Software 2024.
 
#ifndef GRAIL_FITNESS_REPOSITORY_H
#define GRAIL_FITNESS_REPOSITORY_H
 
#include "Individual.hh"
 
#include <unordered_map>
#include <vector>
#include <memory>
#include <numeric>
#include <algorithm>
#include <fstream>
#include <sstream>
#include <iostream>
 
namespace grail
{
namespace evolution
{
    class FitnessRepository final
    {
        struct IndividualHash
        {
            std::size_t operator()(const Individual* individual) const
            {
                return individual->GetHashCode();
            }
        };
 
        struct IndividualEqual
        {
            bool operator()(const Individual* lhs, const Individual* rhs) const
            {
                return lhs->Equals(*rhs);
            }
        };
 
    public:
        FitnessRepository(size_t maxSamplesPerIndividual = 100);
 
        std::size_t GetSampleCount(const Individual& individual) const;
 
        bool TryGetFitness(const Individual& individual, double& fitness) const;
 
        // Call this method after a new fitness evaluation has been performed.
        // Stores an individual in the repository along with its current fitness.
        // Then updates its fitness to the average value of the current and past fitness value.
        void AddSampleWithFitnessUpdate(Individual& individual);
 
        void Serialize(const std::string& filename) const;
 
        bool Deserialize(const std::string& filename, const Individual& populationRepresentative);
 
    private:
        std::unordered_map<const Individual*, std::vector<double>, IndividualHash, IndividualEqual> individualFitnessEvaluations{};
        std::vector<std::unique_ptr<Individual>> ownedIndividuals{};
        std::size_t maxSamples;
    };
}
}
#endif //GRAIL_FITNESS_REPOSITORY_H