note 89898 added to book.array

Converting a linear array (like a mysql record set) into a tree, or multi-dimensional array can be a real bugbear. Capitalizing on references in PHP, we can 'stack' an array in one pass, using one loop, like this: <?php # array_stack() # Original idea from: # http://www.ideashower.com/our_solutions/ # create-a-parent-child-array-structure-in-one-pass/ function array_stack (&$a, $p = '@parent', $c = '@children') { $l = $t = array(); foreach ($a AS $key => $val): if (!$val[$p]) $t[$key] =& $l[$key]; else $l[$val[$p]][$c][$key] =& $l[$key]; $l[$key] = (array)$l[$key] + $val; endforeach; return $a = array('tree' => $t, 'leaf' => $l); } # Example: $node = array(); $node[1] = array('@parent' => 0, 'title' => 'I am node 1.'); # ^-----------------------v Link @parent value to key. $node[2] = array('@parent' => 1, 'title' => 'I am node 2.'); $node[3] = array('@parent' => 2, 'title' => 'I am node 3.'); $node[4] = array('@parent' => 1, 'title' => 'I am node 4.'); $node[5] = array('@parent' => 4, 'title' => 'I am node 5.'); array_stack($node); $node['leaf'][1]['title'] = 'I am node one.'; $node['leaf'][2]['title'] = 'I am node two.'; $node['leaf'][3]['title'] = 'I am node three.'; $node['leaf'][4]['title'] = 'I am node four.'; $node['leaf'][5]['title'] = 'I am node five.'; echo '<pre>',print_r($node['tree'],TRUE),'</pre>'; ?> Note that there's no parameter checking on the array value, but this is only to keep the function size small. One could easily a quick check in there to make sure the $a parameter was in fact an array. Hope you find it useful. Huge thanks to Nate Weiner of IdeaShower.com for providing the original function I built on. ---- Server IP: 69.147.83.197 Probable Submitter: 72.192.19.244 ---- Manual Page -- http://www.php.net/manual/en/book.array.php Edit -- https://master.php.net/note/edit/89898 Del: integrated -- https://master.php.net/note/delete/89898/integrated Del: useless -- https://master.php.net/note/delete/89898/useless Del: bad code -- https://master.php.net/note/delete/89898/bad+code Del: spam -- https://master.php.net/note/delete/89898/spam Del: non-english -- https://master.php.net/note/delete/89898/non-english Del: in docs -- https://master.php.net/note/delete/89898/in+docs Del: other reasons-- https://master.php.net/note/delete/89898 Reject -- https://master.php.net/note/reject/89898 Search -- https://master.php.net/manage/user-notes.php