Creates multidimensional array of all categories in a WP blog

get_category_array.php

$categories = get_categories( array(
    'orderby' => 'name',
    'order'   => 'ASC',
	'hide_empty' => 0,
) );
 
 
$cats_tree = get_cat_tree(0,$categories);
function get_cat_tree($parent,$categories) {
    $result = array();
    foreach($categories as $category){
        if ($parent == $category->category_parent) {
            $category->children = get_cat_tree($category->cat_ID,$categories);
            $result[] = $category;
        }
    }
    return $result;
}

Taken from https://stackoverflow.com/questions/6865207/php-wordpress-get-a-multidimensional-array-of-category-objects