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CRAP | |
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| KNearestNeighbors | |
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| __construct | |
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| predictSample | |
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| kNeighborsDistances | |
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| <?php | |
| declare (strict_types = 1); | |
| namespace Phpml\Classification; | |
| use Phpml\Helper\Predictable; | |
| use Phpml\Helper\Trainable; | |
| use Phpml\Math\Distance; | |
| use Phpml\Math\Distance\Euclidean; | |
| class KNearestNeighbors implements Classifier | |
| { | |
| use Trainable, Predictable; | |
| /** | |
| * @var int | |
| */ | |
| private $k; | |
| /** | |
| * @var Distance | |
| */ | |
| private $distanceMetric; | |
| /** | |
| * @param int $k | |
| * @param Distance|null $distanceMetric (if null then Euclidean distance as default) | |
| */ | |
| public function __construct(int $k = 3, Distance $distanceMetric = null) | |
| { | |
| if (null === $distanceMetric) { | |
| $distanceMetric = new Euclidean(); | |
| } | |
| $this->k = $k; | |
| $this->samples = []; | |
| $this->labels = []; | |
| $this->distanceMetric = $distanceMetric; | |
| } | |
| /** | |
| * @param array $sample | |
| * | |
| * @return mixed | |
| */ | |
| protected function predictSample(array $sample) | |
| { | |
| $distances = $this->kNeighborsDistances($sample); | |
| $predictions = array_combine(array_values($this->labels), array_fill(0, count($this->labels), 0)); | |
| foreach ($distances as $index => $distance) { | |
| ++$predictions[$this->labels[$index]]; | |
| } | |
| arsort($predictions); | |
| reset($predictions); | |
| return key($predictions); | |
| } | |
| /** | |
| * @param array $sample | |
| * | |
| * @return array | |
| * | |
| * @throws \Phpml\Exception\InvalidArgumentException | |
| */ | |
| private function kNeighborsDistances(array $sample): array | |
| { | |
| $distances = []; | |
| foreach ($this->samples as $index => $neighbor) { | |
| $distances[$index] = $this->distanceMetric->distance($sample, $neighbor); | |
| } | |
| asort($distances); | |
| return array_slice($distances, 0, $this->k, true); | |
| } | |
| } |