data-structures 0.1.3

Extra Python Data Structures - bags/multisets and setlists

collections_extended README
###########################

:Author: Michael Lenzen
:Copyright: 2014 Michael Lenzen
:License: Apache License, Version 2.0
:Project Homepage: https://github.com/mlenzen/python-data-structures

.. contents::

.. code:: python

Getting Started
===============

>>> from collections_extended import bag, setlist
>>> b = bag('abracadabra')
>>> b.count('a')
5
>>> sl = setlist('abracadabra')
>>> sl[3]
'c'
>>> sl[-1]
'd'

Installation
============
pip install data-structures

Overview
========

This package includes one module - ``collections_extended``. This
module extends the built-in collections module to include a ``bag`` class,
AKA multiset, and a ``setlist`` class, which is a list of unique elements or
an ordered set depending on how you look at it. There are also frozen
(hashable) varieties of each included. Finally, all collections are
abstracted into one Collection abstract base class and a Collection factory
is provided where you can create a Collection by specifying the properties
unique, ordered and mutable.


Usage
=====
``from collections_extended import bag, frozenbag, setlist, frozensetlist``

Classes
=======
There are four new classes provided:

bag
This is a bag AKA multiset.
frozenbag
This is a frozen (hashable) version of a bag.
setlist
An ordered set or a list of unique elements depending on how you look at it.
frozensetlist
This is a frozen (hashable) version of a setlist.

bag
---
Bags have constant time inclusion testing but can only contain hashable elements. See http://en.wikipedia.org/wiki/Multiset

- ``count(elem)``
Returns the count of elem in the bag. O(1)
- ``num_unique_elements()``
Returns the number of unique elements in the bag. O(1)
- ``unique_elements()``
Returns a set of all the unique elements in the bag. O(1)
- ``nlargest(n=None)``
Returns the n most common elements and their counts from most common to least. If n is None then all elements are returned. O(n log n)
- ``copy()``
Returns a shallow copy of self. O(self.num_unique_elements())
- ``cardinality()``
Returns the cardinality of this bag. Same as ``len(self)``. O(1)
- ``underlying_set()``
Returns the underlying set. Same as ``self.unique_elements()``.
- ``multiplicity(elem)``
Same as ``self.count(elem)``
- ``isdisjoint(other: Iterable)``
Tests if self is disjoint with any other Iterable. O(len(other))

The following are only for mutable bags (not frozenbags).

- ``pop()``
- ``add(elem)``
- ``discard(elem)``
- ``remove(elem)``
- ``clear()``

setlist
-------
A ``setlist`` is an ordered collection with unique elements. The class
implements Sequence and Set and should be able to be used as a drop in
replacement for a set or list of you want to add the add an additional
constraint of ordering or uniqueness. It it more than just an ordered Set
in that the elements are accessible by index (ie. not just a linked set).

Collection Factory
==================
A Collection factory is provided where you can specify whether you want the
Collection returned to be mutable, have unique elements and/or be ordered. If
an Iterable object is passed the Collection will be filled from it, otherwise
it will be empty.

``collection(it = None, mutable=True, unique=False, ordered=False)``