Sort::Tree implements a mechanism for sorting a list of objects into a
tree structure and flattening it back into a list.  Among other things,
this is useful for displaying database queries in hierarchical views,
such as nested categories, parent-child relationships, threaded
discussions, and so forth.

Trees have a lot to do with Graph theory, so if this module doesn't suit
your fancy, have a look at the Graph:: Perl modules for an academically
oriented implementation that employs vertex, edge, and node operations.

For more information on how to use the perl module, see the
pod documentation via the command
  perldoc Sort::Tree
or, after installation, view the man pages with
  man Sort::Tree

WWW: http://search.cpan.org/dist/Sort-Tree/