79 lines
1.8 KiB
PHP
79 lines
1.8 KiB
PHP
<?php
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declare(strict_types=1);
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namespace Phpml\FeatureSelection;
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use Phpml\Exception\InvalidArgumentException;
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use Phpml\Exception\InvalidOperationException;
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use Phpml\FeatureSelection\ScoringFunction\ANOVAFValue;
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use Phpml\Transformer;
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final class SelectKBest implements Transformer
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{
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/**
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* @var ScoringFunction
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*/
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private $scoringFunction;
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/**
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* @var int
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*/
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private $k;
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/**
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* @var array|null
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*/
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private $scores = null;
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/**
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* @var array|null
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*/
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private $keepColumns = null;
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public function __construct(int $k = 10, ?ScoringFunction $scoringFunction = null)
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{
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if ($scoringFunction === null) {
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$scoringFunction = new ANOVAFValue();
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}
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$this->scoringFunction = $scoringFunction;
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$this->k = $k;
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}
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public function fit(array $samples, ?array $targets = null): void
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{
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if ($targets === null || count($targets) === 0) {
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throw new InvalidArgumentException('The array has zero elements');
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}
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$this->scores = $sorted = $this->scoringFunction->score($samples, $targets);
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if ($this->k >= count($sorted)) {
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return;
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}
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arsort($sorted);
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$this->keepColumns = array_slice($sorted, 0, $this->k, true);
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}
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public function transform(array &$samples, ?array &$targets = null): void
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{
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if ($this->keepColumns === null) {
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return;
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}
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foreach ($samples as &$sample) {
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$sample = array_values(array_intersect_key($sample, $this->keepColumns));
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}
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}
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public function scores(): array
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{
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if ($this->scores === null) {
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throw new InvalidOperationException('SelectKBest require to fit first to get scores');
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}
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return $this->scores;
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}
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}
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