Population.hpp

/*
 * Name:	GGA - Generic Genetic Algorithm
 * Author:	Lucas Costa Campos
 * Email: 	Rmk236@gmail.com
 * Version:	0.1
 * License:	GNU General Public License
 * 		Copyright: 2013 Lucas Costa Campos
 * Website: 	https://github.com/LucasCampos/
 */

/*
 *     This file is part of GGA
 *
 *     POPS 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.
 * 
 *     This program 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 this program; if not, write to the Free Software
 *     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 * */
#ifndef POPULATION_HPP
#define POPULATION_HPP

#include <vector>
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <tuple>
#include <algorithm>

template <class Ind>
struct Population {

	std::vector<Ind> individuals;
	std::vector<Ind> newIndividuals;
	int N;
	int hN;
	double mutateProb;

	Population(const std::vector<Ind>& ind, double mp):individuals(ind), mutateProb(mp){
	
		N=ind.size();
		newIndividuals.reserve(N);
		hN=N/2;
#ifdef DEBUG
		if ((N%2==1)) 
			std::cout << "Set an even number of individuals" << std::endl;
#endif
	}


	std::tuple<Ind,Ind> MakeChildren(const Ind& parA, const Ind& parB) const {
	
		Ind chlA,chlB;
		std::array<Ind,4> ind = parA.CrossOver(parB);
		std::sort(ind.begin(),ind.end(),[](const Ind& x, const Ind& y){return x.fitness > y.fitness;});
		return std::make_tuple(ind[0],ind[1]);
	}

	void CrossEveryone() {
		Ind g1, g2;
		for (int i=0; i<hN; i++) {
			const int idx1 = rand()%N;
			const int idx2 = rand()%N; //Not guaranteed to be diff from idx1
			std::tie(g1,g2) = MakeChildren(individuals[idx1],individuals[idx2]);
			newIndividuals.push_back(g1);
			newIndividuals.push_back(g2);
		}
	}

	void MutateEveryone() {
		for (int i=0; i<N; i++) {
			newIndividuals[i].Mutate(mutateProb);
		}
	}

	void MakeNewGen() {
		newIndividuals.clear();
		CrossEveryone();
		MutateEveryone();
		individuals = newIndividuals;
	}

	std::vector<double> GetAnswers() {
		std::vector<double> ans; ans.reserve(N);
		std::transform(individuals.begin(),individuals.end(),ans.begin(),[](const Ind& x){return x.fitness;});
		std::sort(ans.begin(), ans.end());
		return ans;
	}
};
#endif