Group a php array to a tree structure

createTreeStructureFromArray.php

$original = array
(
    "1" => array
    (
        "id" => 1,
        "type" => "mtb",
        "brand" => "scott",
        "name" => "scott1"
    ),
    array
    (
        "id" => 2,
        "type" => "mtb",
        "brand" => "cube",
        "name" => "cube1"
    ),
    array
    (
        "id" => 3,
        "type" => "race",
        "brand" => "cube",
        "name" => "cuberace1"
    ),
    array
    (
        "id" => 4,
        "type" => "race",
        "brand" => "giant",
        "name" => "giant1"
    ),
    array
    (
        "id" => 5,
        "type" => "mtb",
        "brand" => "cube",
        "name" => "cube2"
    )
);
 
echo "<pre>";
print_r($original);
echo "</pre>";
 
$converted = array();
$keys = array('type', 'brand');
$level = 0;
 
$converted = createTree($original, $keys);
 
echo "<pre>";
print_r($converted);
echo "</pre>";
 
function createTree($original, $keys, $level = 0)
{
  $converted = array();
  $key = $keys[$level];
  $isDeepest = sizeof($keys) -1 == $level;
 
  $level++;
  $filtered = array();
 
  foreach ($original as $k => $subArray)
  {
    $thisLevel = $subArray[$key];
    if($isDeepest) $converted[$thisLevel][] = $subArray;
    else $converted[$thisLevel] = array();
 
    $filtered[$thisLevel][] = $subArray;
  }
 
  if(!$isDeepest)
  {
    foreach (array_keys($converted) as $value)
    {
      $converted[$value] = createTree($filtered[$value], $keys, $level);
    }
  }
 
  return $converted;
}