ERWA.hpp

/*
 
Copyright © 2023-24 Sean Holden. All rights reserved.
 
*/
/*
 
This file is part of Connect++.
 
Connect++ is free software: you can redistribute it and/or modify it 
under the terms of the GNU General Public License as published by the 
Free Software Foundation, either version 3 of the License, or (at your 
option) any later version.
 
Connect++ is distributed in the hope that it will be useful, but WITHOUT 
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 
more details.
 
You should have received a copy of the GNU General Public License along 
with Connect++. If not, see <https://www.gnu.org/licenses/>. 
 
*/
 
#ifndef ERWA_HPP
#define ERWA_HPP
 
#include <iostream>
#include <vector>
#include <math.h>
 
#include "Parameters.hpp"
 
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/bernoulli_distribution.hpp>
#include <boost/random/uniform_int_distribution.hpp>
 
using std::vector;
using std::cerr;
using std::endl;
using std::ostream;
 
class ERWA {
private:
    static boost::random::mt19937 random_generator;
    boost::random::bernoulli_distribution<> p;
    boost::random::uniform_int_distribution<> p2;
    vector<double> r_hat;
    double epsilon;
    double alpha;
    size_t K;
    size_t n;
    bool epsilon_greedy;
    bool alpha_is_1_over_n;
    bool choose_next;
    size_t choice;
    size_t find_max() const;
public:
    ERWA() = delete;
    ERWA(size_t, bool=true, bool=true); 
 
    inline size_t get_choice() const {
        return choice;
    }
    inline void set_epsilon(double _e) {
        epsilon = _e;
        boost::random::bernoulli_distribution<> new_p(_e);
        p = new_p;
    }
    inline void set_alpha(double _a) {
        alpha = _a;
    }
    size_t choose();
    void reward(double);
 
    friend ostream& operator<<(ostream&, const ERWA&);
};
 
#endif