Adds left and right values to the dataframe

Left and right values are used to store hierarchical data using the concept of modified preorder tree traversal. See https://www.sitepoint.com/hierarchical-data-database-3/

Usage

tree_add_mptt(data)

Arguments

data

Dataframe with the columns tree_id, tree_parent, tree_thread, tree_level, tree_order

Value

Dataframe with lft and rght values