[Summary view]

Differences Between: [Versions 311 and 400] [Versions 311 and 401] [Versions 311 and 402] [Versions 311 and 403]

   1  <?php
   2  
   3  declare(strict_types=1);
   4  
   5  namespace Phpml\FeatureSelection;
   6  
   7  use Phpml\Exception\InvalidArgumentException;
   8  use Phpml\Exception\InvalidOperationException;
   9  use Phpml\FeatureSelection\ScoringFunction\ANOVAFValue;
  10  use Phpml\Transformer;
  11  
  12  final class SelectKBest implements Transformer
  13  {
  14      /**
  15       * @var ScoringFunction
  16       */
  17      private $scoringFunction;
  18  
  19      /**
  20       * @var int
  21       */
  22      private $k;
  23  
  24      /**
  25       * @var array|null
  26       */
  27      private $scores = null;
  28  
  29      /**
  30       * @var array|null
  31       */
  32      private $keepColumns = null;
  33  
  34      public function __construct(int $k = 10, ?ScoringFunction $scoringFunction = null)
  35      {
  36          if ($scoringFunction === null) {
  37              $scoringFunction = new ANOVAFValue();
  38          }
  39  
  40          $this->scoringFunction = $scoringFunction;
  41          $this->k = $k;
  42      }
  43  
  44      public function fit(array $samples, ?array $targets = null): void
  45      {
  46          if ($targets === null || count($targets) === 0) {
  47              throw new InvalidArgumentException('The array has zero elements');
  48          }
  49  
  50          $this->scores = $sorted = $this->scoringFunction->score($samples, $targets);
  51          if ($this->k >= count($sorted)) {
  52              return;
  53          }
  54  
  55          arsort($sorted);
  56          $this->keepColumns = array_slice($sorted, 0, $this->k, true);
  57      }
  58  
  59      public function transform(array &$samples): void
  60      {
  61          if ($this->keepColumns === null) {
  62              return;
  63          }
  64  
  65          foreach ($samples as &$sample) {
  66              $sample = array_values(array_intersect_key($sample, $this->keepColumns));
  67          }
  68      }
  69  
  70      public function scores(): array
  71      {
  72          if ($this->scores === null) {
  73              throw new InvalidOperationException('SelectKBest require to fit first to get scores');
  74          }
  75  
  76          return $this->scores;
  77      }
  78  }