collections-extended

README

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Documentation: http://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:

• a bag class, AKA multiset,
• a setlist class, which is a unique list or ordered set,
• a bijection class, RangeMap which is a mapping from ranges to values and
• a IndexedDict class, which is an ordered mapping whose elements can be accessed using index, in addition to key.

There are also frozen (hashable) varieties of bags and setlists.

Compatible with and tested against Python 3.6, 3.7, 3.8, 3.9, 3.10 & PyPy3.

Getting Started

.. code-block:: python

>>> 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``

Classes

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: 2021 Michael Lenzen :License: Apache License, Version 2.0 :Project Homepage: https://github.com/mlenzen/collections-extended