Use a genetic algorithm to evolve populations of bit strings.
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//
#include "BitEvolver/Includes.h"
#include "BitEvolver/Random.h"
#include "BitEvolver/Population.h"
#include "BitEvolver/Breeder.h"
#include "BitEvolver/RouletteWheel.h"
#include "BitEvolver/Chromosome.h"
//
#include <memory>
#include <vector>
#include <mutex>
#include <iostream>
#include <algorithm>
#include <thread>
#include <functional>
#include <string>
#include <sstream>
//
namespace BitEvolver
{
//
using std::string;
using std::stringstream;
using std::cout;
using std::endl;
//
Population::Population()
{
//
this->InitRandomGenerator();
this->InitRouletteWheel();
this->InitBreeder();
//
this->Reset();
}
//
void Population::Reset()
{
//
this->evolution_number = 0;
this->population_size = Population::DEFAULT_POPULATION_SIZE;
//
this->SetElitismType(Population::DEFAULT_ELITISM_TYPE);
this->SetElitismRate(Population::DEFAULT_ELITISM_RATE);
this->SetElitismCount(Population::DEFAULT_ELITISM_COUNT);
//
this->SetCrossoverType(Population::DEFAULT_CROSSOVER_TYPE);
this->SetCrossoverOrder(Population::DEFAULT_CROSSOVER_ORDER);
this->SetCrossoverBounds(Population::DEFAULT_CROSSOVER_BOUNDS);
this->SetCrossoverPoint(Population::DEFAULT_CROSSOVER_POINT);
this->SetCrossoverPointStandardDeviation(Population::DEFAULT_CROSSOVER_POINT_STD);
//
this->SetMutationRate(Population::DEFAULT_MUTATION_RATE);
//
this->RandomizePopulation(this->population_size);
}
//
void Population::ClearPopulation()
{
//
this->chromosomes.clear();
this->evolution_number = 0;
}
//
void Population::InitRandomPopulation(int _population_size, int _bit_length)
{
//
this->population_size = _population_size;
//
this->RandomizePopulation(_bit_length);
}
//
void Population::RandomizePopulation(int _bit_length)
{
//
std::shared_ptr<Chromosome> chromosome;
int i;
//
this->ClearPopulation();
for ( i=0; i<this->population_size; i++ ) {
//
chromosome = std::shared_ptr<Chromosome>(
new Chromosome( this->random, _bit_length )
);
this->chromosomes.push_back(chromosome);
}
}
//
void Population::PopulationChanged()
{
//
this->population_needs_sorting = true;
}
//
std::vector<std::shared_ptr<Chromosome>> Population::GetChromosomes()
{
return this->chromosomes;
}
//
void Population::GetChromosomes(std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes)
{
//
_chromosomes->clear();
for ( std::shared_ptr<Chromosome> chromosome : this->chromosomes) {
_chromosomes->push_back(chromosome);
}
}
//
std::shared_ptr<Chromosome> Population::GetChampion()
{
//
this->EnsureSortedPopulation();
//
if ( this->chromosomes.size() > 0 ) {
return this->chromosomes[0];
}
return nullptr;
}
//
double Population::GetAverageFitness()
{
return this->GetAverageFitness(this->chromosomes);
}
//
double Population::GetAverageFitness(std::vector<std::shared_ptr<Chromosome>> _chromosomes)
{
//
double fitness_sum;
double fitness_average;
//
fitness_sum = 0;
for ( std::shared_ptr<Chromosome> chromosome : _chromosomes ) {
fitness_sum += chromosome->GetFitness();
}
//
fitness_average = 0;
if ( _chromosomes.size() > 0 ) {
fitness_average = fitness_sum / _chromosomes.size();
}
return fitness_average;
}
//
void Population::SetCrossoverType(Enums::CrossoverType t)
{
//
this->crossover_type = t;
}
//
Enums::CrossoverType Population::GetCrossoverType()
{
//
return this->crossover_type;
}
//
void Population::SetCrossoverOrder(Enums::CrossoverOrder o)
{
//
this->crossover_order = o;
}
//
Enums::CrossoverOrder Population::GetCrossoverOrder()
{
//
return this->crossover_order;
}
//
void Population::SetCrossoverBounds(Enums::CrossoverBounds b)
{
//
this->crossover_bounds = b;
}
//
Enums::CrossoverBounds Population::GetCrossoverBounds()
{
//
return this->crossover_bounds;
}
//
void Population::SetCrossoverPoint(double p)
{
//
this->crossover_point = p;
}
//
double Population::GetCrossoverPoint()
{
//
return this->crossover_point;
}
//
void Population::SetCrossoverPointStandardDeviation(double std)
{
//
this->crossover_point_std = std;
}
//
double Population::GetCrossoverPointStandardDeviation()
{
//
return this->crossover_point_std;
}
//
void Population::SetMutationRate(double r)
{
//
this->mutation_rate = r;
}
//
double Population::GetMutationRate()
{
//
return this->mutation_rate;
}
//
void Population::SetElitismType(Enums::ElitismType t)
{
//
this->elitism_type = t;
}
//
Enums::ElitismType Population::GetElitismType()
{
//
return this->elitism_type;
}
//
void Population::SetElitismRate(double r)
{
//
this->elitism_rate = r;
}
//
double Population::GetElitismRate()
{
//
return this->elitism_rate;
}
//
void Population::SetElitismCount(int c)
{
//
this->elitism_count = c;
}
//
int Population::GetElitismCount()
{
//
return this->elitism_count;
}
//
void Population::EvaluateFitness(std::function<double(std::shared_ptr<Chromosome>)> evaluation_callback)
{
//
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes_copy;
std::vector<std::shared_ptr<std::thread>> threads;
std::shared_ptr<std::thread> thread;
int
threads_count,
i
;
// Make a new vector containing all current chromosomes
this->population_modification_mutex.lock();
_chromosomes_copy = std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>>(
new std::vector<std::shared_ptr<Chromosome>>()
);
for ( i=0; i<(int)this->chromosomes.size(); i++ ) {
_chromosomes_copy->push_back( this->chromosomes[i] );
}
this->population_modification_mutex.unlock();
// Spawn threads
threads_count = this->GetThreadCountSuggestion();
for ( i=0; i<threads_count; i++) {
//
thread = std::shared_ptr<std::thread>(
new std::thread(&Population::EvaluateFitness_Thread, this, _chromosomes_copy, evaluation_callback)
);
threads.push_back(thread);
}
// Wait for threads to finish
for ( i=0; i<threads_count; i++ ) {
threads[i]->join();
}
}
//
void Population::EvaluateError(std::function<double(std::shared_ptr<Chromosome>)> evaluation_callback)
{
//
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes_copy;
std::vector<std::shared_ptr<std::thread>> threads;
std::shared_ptr<std::thread> thread;
int
threads_count,
i
;
// Make a new vector containing all current chromosomes
this->population_modification_mutex.lock();
_chromosomes_copy = std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>>(
new std::vector<std::shared_ptr<Chromosome>>()
);
for ( i=0; i<(int)this->chromosomes.size(); i++ ) {
_chromosomes_copy->push_back( this->chromosomes[i] );
}
this->population_modification_mutex.unlock();
// Spawn threads
threads_count = this->GetThreadCountSuggestion();
for ( i=0; i<threads_count; i++) {
//
thread = std::shared_ptr<std::thread>(
new std::thread(&Population::EvaluateError_Thread, this, _chromosomes_copy, evaluation_callback)
);
threads.push_back(thread);
}
// Wait for threads to finish
for ( i=0; i<threads_count; i++ ) {
threads[i]->join();
}
}
//
void Population::Evolve()
{
//
std::shared_ptr<std::vector< std::shared_ptr<Chromosome> > > population_new;
//
if ( this->chromosomes.size() == 0 ) {
return;
}
//
this->EnsureSortedPopulation();
//
population_new = std::shared_ptr<
std::vector<
std::shared_ptr<Chromosome>
>
>(
new std::vector<std::shared_ptr<Chromosome>>()
);
// Breed the new population
this->BreedNewPopulation(population_new, (int)this->chromosomes.size());
// Replace old population with the new
this->chromosomes = *population_new;
this->evolution_number++;
//
this->PopulationChanged();
}
//
int Population::GetEvolutionNumber()
{
return this->evolution_number;
}
//
void Population::PrintPopulation()
{
//
this->EnsureSortedPopulation();
this->PrintPopulation(this->chromosomes);
}
//
void Population::PrintPopulation(std::vector<std::shared_ptr<Chromosome>> _chromosomes)
{
//
for ( std::shared_ptr<Chromosome> chromosome : chromosomes ) {
cout << chromosome->ToString() << endl;
}
cout << "Average Fitness --> " << this->GetAverageFitness(_chromosomes) << endl;
}
//
void Population::InitRandomGenerator()
{
//
this->random = std::shared_ptr<Random>(
new Random()
);
}
//
void Population::InitRouletteWheel()
{
//
this->roulette_wheel = std::shared_ptr<RouletteWheel>(
new RouletteWheel()
);
}
//
void Population::InitBreeder()
{
//
if ( !this->random ) {
throw std::runtime_error("Population::InitBreeder() - Should come after InitRandomGenerator()");
}
//
this->breeder = std::shared_ptr<Breeder>(
new Breeder( this->random )
);
}
//
void Population::EnsureSortedPopulation()
{
//
if ( !this->population_needs_sorting ) {
return;
}
// Yay std::sort
std::sort(
this->chromosomes.begin(),
this->chromosomes.end(),
[]( std::shared_ptr<Chromosome>& left, std::shared_ptr<Chromosome>& right ) -> bool
{
//
if ( left->GetFitness() > right->GetFitness() ) {
return true;
}
return false;
}
);
//
this->population_needs_sorting = false;
}
//
void Population::BreedNewPopulation(std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> population_new, int size)
{
//
std::vector<std::shared_ptr<std::thread>> threads;
std::shared_ptr<std::thread> thread;
int
thread_count,
i
;
// First, populate the roulette wheel
this->roulette_wheel->SetChromosomes(this->chromosomes);
// Next, seed the population with elites
this->SeedPopulationWithElites(population_new);
// Next, breed until we've reached our new size
thread_count = this->GetThreadCountSuggestion();
for ( i=0; i<thread_count; i++) {
thread = std::shared_ptr<std::thread>(
new std::thread(&Population::BreedNewPopulation_Thread, this, population_new, size)
);
threads.push_back(thread);
}
for ( i=0; i<(int)threads.size(); i++) {
threads[i]->join();
}
// Finally, reset the fitness of the new population
for ( i=0; i<(int)population_new->size(); i++ ) {
population_new->at(i)->ResetFitness();
}
}
//
void Population::BreedNewPopulation_Thread(std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> population_new, int size)
{
//
std::shared_ptr<Chromosome> kiddo;
//
while ( (int)population_new->size() < size )
{
//
kiddo = this->BreedChild();
// Mutexed
this->breed_mutex.lock();
if ( (int)population_new->size() < size ) {
population_new->push_back(kiddo);
}
this->breed_mutex.unlock();
}
}
//
int Population::DetermineEliteCount()
{
//
int count;
//
switch( this->elitism_type )
{
//
default:
case Enums::ElitismType::None:
count = 0;
break;
//
case Enums::ElitismType::Absolute:
count = this->elitism_count;
break;
//
case Enums::ElitismType::Rate:
count = floor( this->chromosomes.size() * this->elitism_rate );
break;
}
return count;
}
//
void Population::SeedPopulationWithElites(std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> population_new)
{
//
std::unique_lock<std::recursive_mutex> lock(this->population_modification_mutex);
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> elites;
std::vector<std::shared_ptr<std::thread>> threads;
std::shared_ptr<std::thread> thread;
int
elites_count,
i
;
// Determine how many elites to copy
elites_count = this->DetermineEliteCount();
elites = std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>>(
new std::vector<std::shared_ptr<Chromosome>>()
);
// First, copy over just the pointers
for ( i=0; i<elites_count && i<(int)this->chromosomes.size(); i++) {
elites->push_back( this->chromosomes[i] );
}
// Then, make them full copies (uses threads)
this->CopyChromosomes(elites, population_new);
}
//
void Population::EvaluateFitness_Thread(
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes,
std::function<double(std::shared_ptr<Chromosome>)> evaluation_callback
)
{
//
std::shared_ptr<Chromosome> chromosome;
double fitness;
//
while (true)
{
// Grab a free chromosome
this->evaluate_fitness_mutex.lock();
chromosome = nullptr;
if ( _chromosomes->size() ) {
chromosome = _chromosomes->at(_chromosomes->size()-1);
_chromosomes->pop_back();
}
this->evaluate_fitness_mutex.unlock();
// Call the evaluation callback
if ( chromosome != nullptr ) {
fitness = evaluation_callback(chromosome);
chromosome->SetFitness(fitness);
}
// We're done if there was nothing to grab
else{
break;
}
}
}
//
void Population::EvaluateError_Thread(
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes,
std::function<double(std::shared_ptr<Chromosome>)> evaluation_callback
)
{
//
std::shared_ptr<Chromosome> chromosome;
double error;
//
while (true)
{
// Grab a free chromosome
this->evaluate_fitness_mutex.lock();
chromosome = nullptr;
if ( _chromosomes->size() ) {
chromosome = _chromosomes->at(_chromosomes->size()-1);
_chromosomes->pop_back();
}
this->evaluate_fitness_mutex.unlock();
// Call the evaluation callback
if ( chromosome != nullptr ) {
error = evaluation_callback(chromosome);
chromosome->SetError(error);
}
// We're done if there was nothing to grab
else{
break;
}
}
}
//
void Population::CopyChromosomes(
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes_source,
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes_destination
)
{
//
std::vector<std::shared_ptr<std::thread>> threads;
std::shared_ptr<std::thread> thread;
int
threads_count,
i
;
// Spawn threads
threads_count = this->GetThreadCountSuggestion();
for ( i=0; i<threads_count; i++) {
//
thread = std::shared_ptr<std::thread>(
new std::thread(&Population::CopyChromosomes_Thread, this, _chromosomes_source, _chromosomes_destination)
);
threads.push_back(thread);
}
// Wait for threads to finish
for ( i=0; i<threads_count; i++ ) {
threads[i]->join();
}
}
//
void Population::CopyChromosomes_Thread(
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes_source,
std::shared_ptr<std::vector<std::shared_ptr<Chromosome>>> _chromosomes_destination
)
{
//
std::shared_ptr<Chromosome>
chromosome_original,
chromosome_copied
;
stringstream ss;
//
while ( _chromosomes_destination->size() < _chromosomes_source->size() )
{
// Grab the next slot
this->copy_chromosomes_mutex.lock();
chromosome_original = nullptr;
chromosome_copied = nullptr;
if ( _chromosomes_destination->size() < _chromosomes_source->size() ) {
//
chromosome_copied = std::shared_ptr<Chromosome>(
new Chromosome(this->random, 0)
);
_chromosomes_destination->push_back(chromosome_copied);
chromosome_original = _chromosomes_source->at(_chromosomes_destination->size()-1);
}
this->copy_chromosomes_mutex.unlock();
// Make a full copy of the original, outside the lock
if ( chromosome_copied && chromosome_original ) {
*chromosome_copied = *chromosome_original;
}
}
}
//
std::shared_ptr<Chromosome> Population::BreedChild()
{
//
std::shared_ptr<Chromosome>
mama, papa, kiddo
;
// Pick two parents
mama = this->roulette_wheel->Spin();
papa = this->roulette_wheel->Spin();
//
kiddo = this->breeder->Breed(
mama, papa,
this->crossover_type,
this->crossover_order,
this->crossover_bounds,
this->crossover_point,
this->crossover_point_std,
this->mutation_rate
);
return kiddo;
}
//
int Population::GetThreadCountSuggestion()
{
//
int thread_count;
//
thread_count = std::thread::hardware_concurrency();
return thread_count;
}
};