PHP Recursive ksort: ksortTree

Working With Trees

When working with tree data structures you often need to craft them in different ways. PHP offers a lot of functions to change the shape of arrays, but often they only go 1 level deep. Trees can count an almost infinite number of levels. Hence we need recursive replacements for our beloved array functions.

ksortTree

ksortTree is the tree version of ksort. It will alphabetically reorder a tree based on its keys.

<?php
/**
 * Recursive alternative to ksort
 *
 * The following code block can be utilized by PEAR's Testing_DocTest
 * <code>
 * // Input //
 * $array = array(
 *	 "c" => array(
 *		 "d" => 4,
 *		 "a" => 1,
 *		 "b" => 2,
 *		 "c" => 3,
 *		 "e" => 5
 *	 ),
 *	 "a" => array(
 *		 "d" => 4,
 *		 "b" => 2,
 *		 "a" => 1,
 *		 "e" => 5,
 *		 "c" => 3
 *	 ),
 *	 "b" => array(
 *		 "d" => 4,
 *		 "b" => 2,
 *		 "c" => 3,
 *		 "a" => 1
 *	 )
 * );
 *
 * // Execute //
 * ksortTree($array);
 *
 * // Show //
 * print_r($array);
 *
 * // expects:
 * // Array
 * // (
 * //	 [a] => Array
 * //		 (
 * //			 [a] => 1
 * //			 [b] => 2
 * //			 [c] => 3
 * //			 [d] => 4
 * //			 [e] => 5
 * //		 )
 * //
 * //	 [b] => Array
 * //		 (
 * //			 [a] => 1
 * //			 [b] => 2
 * //			 [c] => 3
 * //			 [d] => 4
 * //		 )
 * //
 * //	 [c] => Array
 * //		 (
 * //			 [a] => 1
 * //			 [b] => 2
 * //			 [c] => 3
 * //			 [d] => 4
 * //			 [e] => 5
 * //		 )
 * //
 * // )
 * </code>
 *
 * @author	Kevin van Zonneveld <kevin@vanzonneveld.net>
 * @copyright 2008 Kevin van Zonneveld (https://kevin.vanzonneveld.net)
 * @license   https://www.opensource.org/licenses/bsd-license.php New BSD Licence
 * @version   SVN: Release: $Id: ksortTree.inc.php 223 2009-01-25 13:35:12Z kevin $
 * @link	  https://kevin.vanzonneveld.net/
 *
 * @param array $array
 */
function ksortTree( &$array )
{
	if (!is_array($array)) {
		return false;
	}

	ksort($array);
	foreach ($array as $k=>$v) {
		ksortTree($array[$k]);
	}
	return true;
}
?>