*/ public function compatibility() : array { return [ DataType::categorical(), ]; } /** * Compute the distance between two vectors. * * @internal * * @param list $a * @param list $b * @return float */ public function compute(array $a, array $b) : float { $distance = 0; foreach ($a as $i => $value) { if ($value !== $b[$i]) { ++$distance; } } return (float) $distance; } /** * Return the string representation of the object. * * @internal * * @return string */ public function __toString() : string { return 'Hamming'; } }