Popular recipes tagged "collections"

namedtuple.abc - abstract base class + mix-in for named tuples (Python)

2011-04-02T02:07:00-07:00

Python recipe 577629 by Jan Kaliszewski (abc, collections, dry, inheritance, namedtuple, shortcuts). Revision 7.

If you need

to define named tuple subclasses (including reusable abstract ones), adding/overriding some methods, in a convenient way;
to have the named tuple ABC (abstract base class) for isinstance/issubclass tests;
or simply would like to define your named tuple classes in a class-syntax-based and DRY way (without repeating type names...)

-- this recipe is for you.

Dynamic Class Construction a la DSLs (Python)

2011-08-13T04:00:46-07:00

Python recipe 577718 by Eric Snow (collections).

So maybe it's not quite a mutable namedtuple. However, I borrowed heavily against the namedtuple implementation for this one.

I wanted to have a collection of classes that described data types without any functionality on them, sort of state holders. However, I wanted to use defaults and I wanted it to be mutable.

I noticed, as I started building my classes, that each was following the same pattern, so I extracted it out into this recipe. Wrapping namedtuple to get the same result would probably be feasible, but I enjoyed doing this too.

The distinction between parameters and properties is mostly one I was maintaining between single objects and collections. Realistically everything could have been parameters.

Yet another roundrobin (Python)

2010-07-19T13:53:41-07:00

Python recipe 577309 by Daniel Cohn (collections, itertools, roundrobin). Revision 2.

This recipe provides a decently simple implementation of a roundrobin using itertools and deque.

Virtual collections (Python)

2010-03-09T03:43:13-08:00

Python recipe 577092 by Chris Leong (collections).

This recipe creates a collection proxy which allows several lists to be treated as one. When the collection proxy is accessed/modified, it is as though the operation was performed one the underlying lists.

Sorted dictionary (Python)

2010-01-20T17:11:59-08:00

Python recipe 576998 by Jan Kaliszewski (collections, dict, dictionary, mapping, sorted, sorteddict). Revision 29.

A simple implementation of a dictionary which always (when applicable) returns keys, values, items (key-value pairs) sorted by keys (inserting/removing order doesn't matter and only keys are important; so please note that it is something different than OrderedDict in Python 3.1/2.7 or Django's SortedDict).