README.rst

README

Documentation:

https://collections-extended.lenzm.net/

GitHub:

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

PyPI:

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

Overview

collections_extended is a pure Python module with no dependencies providing extra collections. The new collections include bags AKA multisets, setlists AKA unique lists or ordered sets, a bijection, a RangeMap which is a mapping from ranges to values, and an IndexedDict class. There are also frozen (hashable) varieties of bags and setlists.

Compatible with and tested against CPython 3.6, 3.7, 3.8, 3.9, 3.10, PyPy3.6, PyPy3.7 & PyPy3.8.

Getting Started

>>> from collections_extended import bag, setlist, bijection, RangeMap, IndexedDict
>>> 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

>>> version = RangeMap()
>>> version[date(2017, 10, 20): date(2017, 10, 27)] = '0.10.1'
>>> version[date(2017, 10, 27): date(2018, 2, 14)] = '1.0.0'
>>> version[date(2018, 2, 14):] = '1.0.1'
>>> version[date(2017, 10, 24)]
'0.10.1'
>>> version[date(2018, 7, 1)]
'1.0.1'
>>> version[date(2018, 6, 30):] = '1.0.2'
>>> version[date(2018, 7, 1)]
'1.0.2'

>>> idict = IndexedDict()
>>> idict['a'] = "A"
>>> idict['b'] = "B"
>>> idict['c'] = "C"
>>> idict.get(key='a')
'A'
>>> idict.get(index=2)
'C'
>>> idict.index('b')
1

Installation

pip install collections-extended

Usage

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

New Collections

There are seven new collections 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)

IndexedDict

A mapping that keeps insertion order and allows access by index.

Python 2

The package no longer supports Python 2. The last version to support Python 2.7, 3.4 & 3.5 was 1.0. No new feature releases will be done for 1.x but any significant bugs that come up may be fixed.

Author:	Michael Lenzen
Copyright:	2022 Michael Lenzen
License:	Apache License, Version 2.0
Project Homepage:	https://github.com/mlenzen/collections-extended