Phpml\Math\Distance\Distance

Complexity

Total Complexity

4

Size/Duplication

Total Lines	61
Duplicated Lines	0 %

Coupling/Cohesion

Components	1
Dependencies	1

Importance

Changes

0

3 Methods

Rating	Name	Duplication	Size	Complexity
A	__construct()	0	4	1
A	distance()	0	13	1
A	deltas()	0	14	2

<?php

declare(strict_types=1);

namespace Phpml\Math\Distance;

use Phpml\Exception\InvalidArgumentException;
use Phpml\Math\Distance as DistanceInterface;

/**
 * Class Distance
 */
abstract class Distance implements DistanceInterface
{
    /**
     * @var float|int
     */
    public $norm = 2;

    /**
     * Distance constructor.
     * @param float $norm
     */
    public function __construct(float $norm = 3.0)
    {
        $this->norm = $norm;
    }

    /**
     * @param array $a
     * @param array $b
     *
     * @return float
     *
     * @throws InvalidArgumentException
     */
    public function distance(array $a, array $b): float
    {
        $norm = $this->norm;

        return array_sum(
                array_map(
                    function ($a) use ($norm) {
                        return $a**$norm;
                    },
                    $this->deltas($a, $b)
                )
            ) ** (1 / $norm);
    }

    /**
     * @param array $a
     * @param array $b
     *
     * @return array
     *
     * @throws InvalidArgumentException
     */
    protected function deltas(array $a, array $b): array
    {
        if (count($a) !== count($b)) {
            throw new InvalidArgumentException('Size of given arrays does not match');
        }

        return array_map(
            function ($a, $b) {
                return abs($a - $b);
            },
            $a,
            $b
        );
    }
}