public function crossoverUniform(Population $population, $selectionMethod = 2, $tournamentSize = 10)
{
$newPopulation = new Population($population->size());
for ($populationIndex = 0; $populationIndex < $population->size(); $populationIndex++) {
$parent1 = $population->getFittestIndividual($populationIndex);
if ($this->crossoverRate > Random::generate() && $populationIndex > $this->elitismCount) {
$offspring = new Individual($parent1->getChromosomeLength());
if ($selectionMethod == 1) {
$parent2 = $this->selectParentRoulette($population);
} else {
if ($selectionMethod == 2) {
if ($tournamentSize <= $population->size()) {
$parent2 = $this->selectParentTournament($population, $tournamentSize);
} else {
throw new Exception("Tournament size larger than populations");
}
}
}
for ($geneIndex = 0; $geneIndex < $parent1->getChromosomeLength(); $geneIndex++) {
if (0.5 > Random::generate()) {
$offspring->setGene($geneIndex, $parent1->getGene($geneIndex));
} else {
$offspring->setGene($geneIndex, $parent2->getGene($geneIndex));
}
}
$newPopulation->setIndividual($populationIndex, $offspring);
} else {
$newPopulation->setIndividual($populationIndex, $parent1);
}
}
return $newPopulation;
}
private function getChildren($couple)
{
$geneCount = $couple[0]->getGeneCount();
$child1 = new Individual($geneCount);
$child2 = new Individual($geneCount);
/* @var Individual[] $couple */
for ($i = 0; $i < count($geneCount); $i++) {
if (rand(0, 1)) {
// Swap gene
$child1->setGene($i, $couple[1]->getGene($i));
$child2->setGene($i, $couple[0]->getGene($i));
} else {
// No gene swap
$child1->setGene($i, $couple[0]->getGene($i));
$child2->setGene($i, $couple[1]->getGene($i));
}
}
return [$child1, $child2];
}
