return only given key from bigger array

get_pkey.php

<?php
/**
 * capture only id from bigger array
 *
 * @param array $array input
 * @param array $pkey  primary key
 *
 * @return array
 */
function array_id($array, $pkey)
{
	$checker = function($value) use ($pkey) {
		if (array_key_exists($pkey, $value)) return $value[$pkey];
	};

	return array_map($checker, $array);
}