Phpml\FeatureExtraction\TfIdfTransformer::transform PHP Method

    public function transform(array &$samples)
    {
        foreach ($samples as &$sample) {
            foreach ($sample as $index => &$feature) {
                $feature = $feature * $this->idf[$index];
            }
        }
    }

 public function testTfIdfTransformation()
 {
     // https://en.wikipedia.org/wiki/Tf-idf
     $samples = [[0 => 1, 1 => 1, 2 => 2, 3 => 1, 4 => 0, 5 => 0], [0 => 1, 1 => 1, 2 => 0, 3 => 0, 4 => 2, 5 => 3]];
     $tfIdfSamples = [[0 => 0, 1 => 0, 2 => 0.602, 3 => 0.301, 4 => 0, 5 => 0], [0 => 0, 1 => 0, 2 => 0, 3 => 0, 4 => 0.602, 5 => 0.903]];
     $transformer = new TfIdfTransformer($samples);
     $transformer->transform($samples);
     $this->assertEquals($tfIdfSamples, $samples, '', 0.001);
 }