private function mutate()
{
// order the populating into most to least fit
$this->actors = $this->get_best_fit($this->population);
// get most fit actors to mutate
$mutators = array_slice($this->actors, 0, $this->breeders);
// clear out the population and rebuild it from the best fit
$this->actors = array();
while (count($this->actors) < $this->population) {
// mix 'em up
shuffle($mutators);
for ($i = 0; $i < $this->breeders; $i++) {
$actor = new Actor();
// get code
$code = $mutators[$i]->get_code();
// chance of mutation...
if ($this->mutate_actor()) {
// find a random spot in the code
$pos = mt_rand(0, strlen($code));
$symbol = substr($actor->symbols, mt_rand(0, strlen($actor->symbols) - 1), 1);
$code = substr_replace($code, $symbol, $pos, 1);
}
// insert the code
$actor->init($code);
// Update the population
$this->actors[] = $actor;
}
}
}