First Commit

vendor/php-ai/php-ml/src/Math/Distance/Distance.php

@@ -0,0 +1,61 @@
+<?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;
+
+    /**
+     * Distance constructor.
+     */
+    public function __construct(float $norm = 3.0)
+    {
+        $this->norm = $norm;
+    }
+
+    /**
+     * @throws InvalidArgumentException
+     */
+    public function distance(array $a, array $b): float
+    {
+        $distance = 0;
+
+        foreach ($this->deltas($a, $b) as $delta) {
+            $distance += $delta ** $this->norm;
+        }
+
+        return $distance ** (1 / $this->norm);
+    }
+
+    /**
+     * @throws InvalidArgumentException
+     */
+    protected function deltas(array $a, array $b): array
+    {
+        $count = count($a);
+
+        if ($count !== count($b)) {
+            throw new InvalidArgumentException('Size of given arrays does not match');
+        }
+
+        $deltas = [];
+
+        for ($i = 0; $i < $count; $i++) {
+            $deltas[] = abs($a[$i] - $b[$i]);
+        }
+
+        return $deltas;
+    }
+}