<?php
  
function treeFromBase($queryResult){
  $tempTree = array();
  foreach($queryResult as $treeElement){
    $tempTree[$treeElement[0]] = array(
      'parent'=>$treeElement[1], 
      'children'=>array()
    );
  }
  
  $resTree = array();
  foreach($tempTree as $elementName=>&$treeElement){
    if($treeElement['parent']==NULL){
      $resTree[$elementName]=&$treeElement;
    }else{
      $tempTree[$treeElement['parent']]['children'][$elementName]=&$treeElement;
    }
  }
  return $resTree;
};

$start = time();

for($i=0; $i<800000; $i++){
$res = treeFromBase(array(
    array('parent_id1',NULL),
    array('parent_id2',NULL),
    array('id1',       'parent_id1'),
    array('id2',       'parent_id2'),
    array('subId2',    'id2'),
    array('subId2.1',  'id2'),
    array('subId1',    'id1'),
    array('subId1.1',  'id1'),
));
}
echo time()-$start;
  
  echo "<pre>";
  var_dump($res);
  echo "</pre>";
  
?>

from time import clock

def treeFromBase(arr):
  tempTree = {}
  for node in arr:
    tempTree[node[0]]={"parent": node[1], "children": {}}
    
  resTree = {}
  for nodeName in tempTree:
    if tempTree[nodeName]["parent"]==None:
      resTree[nodeName]=tempTree[nodeName]
    else:
      tempTree[tempTree[nodeName]["parent"]]["children"][nodeName]=tempTree[nodeName]
  
  return resTree

def application(environ, start_response):
  start = clock();
  for i in range(800000):
    res = treeFromBase([
      ['parent_id1',None],
      ['parent_id2',None],
      ['id1', 'parent_id1'],
      ['id2', 'parent_id2'],
      ['subId2', 'id2'],
      ['subId2.1', 'id2'],
      ['subId1', 'id1'],
      ['subId1.1', 'id1']
    ])

  status = '200 OK'
  output = (str)(clock()-start)+repr(res)
  response_headers = [('Content-type', 'text/plain'),
                      ('Content-Length', str(len(output)))]
  start_response(status, response_headers)
   
  return [output]

myVar = [x**2 for x in range(2, 100)];

myVar = [x**2 for x in range(2, 100) if simple(x) else x**3];