dictionary setdefault

[Sean O'Donnell]

A nice recipe using the idioms discussed tonight

http://code.activestate.com/recipes/66516/

[Michael Twomey]

Also, the defaultdict class (in python 2.5 onwards) lets you specify a
factory function instead of passing in the default:

http://docs.python.org/library/collections.html#collections.defaultdict

This is particularly useful for cases where the default value takes a
little while to construct or for shaving a few more lines off your
code.

(In python 2.6 defaultdict is right beside my new favourite class,
namedtuple: http://docs.python.org/library/collections.html#collections.namedtuple)

mick

[Tim Kersten]

Sweeeeet namedtuples! :-) I like.