Online PHP editor | output for s2PNC

<?php header('Content-Type: application/json; charset="utf-8"'); /** * Helper function * * @param array $d flat data, implementing a id/parent id (adjacency list) structure * @param mixed $r root id, node to return * @param string $pk parent id index * @param string $k id index * @param string $c children index * @return array */ function makeRecursive($d, $r = 0, $pk = 'parent', $k = 'id', $c = 'children') { $m = array(); foreach ($d as $e) { isset($m[$e[$pk]]) ?: $m[$e[$pk]] = array(); isset($m[$e[$k]]) ?: $m[$e[$k]] = array(); $m[$e[$pk]][] = array_merge($e, array($c => &$m[$e[$k]])); } return $m[$r][0]; // remove [0] if there could be more than one root nodes } echo json_encode(makeRecursive(array( array('id' => 5273, 'parent' => 0, 'name' => 'John Doe'), array('id' => 6032, 'parent' => 5273, 'name' => 'Sally Smith'), array('id' => 6034, 'parent' => 6032, 'name' => 'Mike Jones'), array('id' => 6035, 'parent' => 6034, 'name' => 'Jason Williams'), array('id' => 6036, 'parent' => 5273, 'name' => 'Sara Johnson'), array('id' => 6037, 'parent' => 5273, 'name' => 'Dave Wilson'), array('id' => 6038, 'parent' => 6037, 'name' => 'Amy Martin'), )));