collections-extended 0.4.0

Extra Python Collections - bags (multisets) and setlists (ordered sets)

Documentation: http://collections-extended.lenzm.net/

GitHub: https://github.com/mlenzen/collections-extended

PyPI: https://pypi.python.org/pypi/collections-extended

Overview

collections_extended, provides a bag class, AKA multiset, a setlist class, which is a unique list or ordered set, a bijection class and RangeMap which is a mapping from ranges to values. There are also frozen (hashable) varieties of bags and setlists.

Tested against Python 2.6, 2.7, 3.2, 3.3, 3.4 & PyPy.

Getting Started

>>> from collections_extended import bag, setlist, bijection, RangeMap
>>> from datetime import date
>>> b = bag('abracadabra')
>>> b.count('a')
5
>>> b.remove('a')
>>> b.count('a')
4
>>> 'a' in b
True
>>> b.count('d')
1
>>> b.remove('d')
>>> b.count('d')
0
>>> 'd' in b
False

>>> sl = setlist('abracadabra')
>>> sl
setlist(('a', 'b', 'r', 'c', 'd'))
>>> sl[3]
'c'
>>> sl[-1]
'd'
>>> 'r' in sl  # testing for inclusion is fast
True
>>> sl.index('d')  # so is finding the index of an element
4
>>> sl.insert(1, 'd')  # inserting an element already in raises a ValueError
Traceback (most recent call last):
...
        raise ValueError
ValueError
>>> sl.index('d')
4

>>> bij = bijection({'a': 1, 'b': 2, 'c': 3})
>>> bij.inverse[2]
'b'
>>> bij['a'] = 2
>>> bij == bijection({'a': 2, 'c': 3})
True
>>> bij.inverse[1] = 'a'
>>> bij == bijection({'a': 1, 'c': 3})
True

>>> us_presidents = RangeMap()
>>> us_presidents[date(1993, 1, 20):date(2001, 1, 20)] = 'Bill Clinton'
>>> us_presidents[date(2001, 1, 20):date(2009, 1, 20)] = 'George W. Bush'
>>> us_presidents[date(2009, 1, 20):] = 'Barack Obama'
>>> us_presidents[date(1995, 5, 10)]
'Bill Clinton'
>>> us_presidents[date(2001, 1, 20)]
'George W. Bush'
>>> us_presidents[date(2021, 3, 1)]
'Barack Obama'
>>> us_presidents[date(2017, 1, 20):] = 'Someone New'
>>> us_presidents[date(2021, 3, 1)]
'Someone New'

Installation

pip install collections-extended

Usage

from collections_extended import bag, frozenbag, setlist, frozensetlist, bijection

Classes

There are six new classes provided:

Bags

bag

This is a bag AKA multiset.

frozenbag

This is a frozen (hashable) version of a bag.

Setlists

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.

Mappings

bijection

A one-to-one mapping.

RangeMap

A mapping from ranges (of numbers/dates/etc)

Author:

Michael Lenzen

Copyright:

2015 Michael Lenzen

License:

Apache License, Version 2.0

Project Homepage:

https://github.com/mlenzen/collections-extended