How to set “Is Anchor” to all categories in magento by custom php script?

Create .php page with below code to set “Is Anchor” to all categories in magento by custom php script.

error_reporting(E_ALL);
ini_set('display_errors', '1');
// Load Up Magento Core
define('MAGENTO', realpath('/'));
require_once(MAGENTO . 'app/Mage.php');
$app = Mage::app();
$categories = Mage::getModel('catalog/category')
->getCollection()
->addAttributeToSelect('*')
->addAttributeToFilter('is_anchor', 0)
->addAttributeToFilter('entity_id', array("gt" => 1))
->setOrder('entity_id');
foreach($categories as $category) {
echo $category->getId() . "t" . $category->getName() . "n";
$category->setIsAnchor(1);
$category->save();
}