php-ml/tests/FeatureExtraction/TfIdfTransformerTest.php

<?php

declare(strict_types=1);

namespace Phpml\Tests\FeatureExtraction;

use Phpml\FeatureExtraction\TfIdfTransformer;
use PHPUnit\Framework\TestCase;

class TfIdfTransformerTest extends TestCase
{
    public function testTfIdfTransformation(): void
    {
        // 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);

        self::assertEqualsWithDelta($tfIdfSamples, $samples, 0.001);
    }
}