164 lines
3.2 KiB
C++
164 lines
3.2 KiB
C++
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//
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#include "BitEvolver/Random.h"
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#include "BitEvolver/Chromosome.h"
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#include "BitEvolver/Breeder.h"
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//
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#include <iostream>
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//
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namespace BitEvolver
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{
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//
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using std::cout;
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using std::endl;
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//
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Breeder::Breeder(std::shared_ptr<Random> _random)
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{
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//
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this->random = _random;
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}
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//
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std::shared_ptr<Chromosome> Breeder::Breed(
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std::shared_ptr<Chromosome> mama,
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std::shared_ptr<Chromosome> papa,
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Enums::CrossoverType crossover_type,
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double crossover_rate,
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double mutation_rate
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)
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{
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//
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std::shared_ptr<Chromosome> kiddo;
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int bit_length;
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//
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bit_length = mama->GetBitCount();
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// Directly copy the mama
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kiddo = std::shared_ptr<Chromosome>(new Chromosome(this->random, bit_length));
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*kiddo = *mama;
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// Apply crossover
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this->ApplyCrossover(kiddo, papa, crossover_type, crossover_rate);
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// Apply mutation
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this->Mutate(kiddo, mutation_rate);
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// Reset kiddo's fitness
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kiddo->ResetFitness();
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return kiddo;
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}
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//
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void Breeder::Mutate(std::shared_ptr<Chromosome> chromosome, double mutation_rate)
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{
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//
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int i, size;
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//
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#warning "For efficiency, let's instead roll the number of bits to flip in advance, and loop that many times (faster than rolling for every bit)"
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//
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size = chromosome->GetBitCount();
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for ( i=0; i<size; i++ ) {
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//
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if ( this->random->RollBool(mutation_rate) ) {
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chromosome->FlipBit(i);
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}
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}
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//
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chromosome->ResetFitness();
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}
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//
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int Breeder::PickRandomCrossoverPoint(std::shared_ptr<Chromosome> chromosome, double crossover_rate)
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{
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//
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double crossover_point_double;
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int crossover_point;
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int bit_count;
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//
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bit_count = chromosome->GetBitCount();
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/**
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Choose a double between [0.0,1.0] for the crossover point.
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Use normal distribution, with the mean to the default point,
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and 1.0 as the std.
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That way, there is still randomness to the crossover point,
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but it still generally sticks near the default
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*/
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crossover_point_double = this->random->GetNormal(crossover_rate, 1.0);
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// Apply to the actual int length
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crossover_point = crossover_point_double * bit_count;
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// Loop around to keep in bounds
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while ( crossover_point < 0 )
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{
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crossover_point += bit_count;
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}
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while ( crossover_point >= bit_count)
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{
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crossover_point -= bit_count;
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}
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return crossover_point;
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}
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//
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void Breeder::ApplyCrossover(
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std::shared_ptr<Chromosome> kiddo,
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std::shared_ptr<Chromosome> parent,
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Enums::CrossoverType crossover_type,
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double crossover_rate
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)
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{
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//
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int
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bits_count,
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crossover_point,
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i
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;
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// Only proceed if using sexual crossover
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if (crossover_type != Enums::CrossoverType::Sexual) {
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return;
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}
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// For now, don't crossover unless the bit lengths are identical
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bits_count = kiddo->GetBitCount();
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if ( parent->GetBitCount() != bits_count ) {
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throw std::runtime_error("Breeder::ApplyCrossover() - Parent incompatible with Kiddo (bit lengths don't match)");
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}
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// Pick random crossover point
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crossover_point = this->PickRandomCrossoverPoint(kiddo, crossover_rate);
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// Begin copying the parent at the crossover point and beyond
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// (not before)
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for ( i=crossover_point; i<bits_count; i++) {
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kiddo->SetBit( i, parent->GetBit(i) );
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}
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//
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kiddo->ResetFitness();
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}
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};
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