Stirling

Installation

The stirling package is available on the Python Package Index (PyPI):

Stirling should work with Python 3.8 or greater. To install:

$ pip install stirling

Examples

A function for generating partitions of a collection into a specific number of non-empty subsets. The number of ways of arranging a set of size n into k non-empty subsets is known at the Stirling Number of the Second Kind or S(n, k).

For example, to find the arrangements of a list of 4 integers into 3 non-empty subsets, use:

>>> from stirling import k_subsets
>>> for arrangement in k_subsets([1, 2, 3, 4], 3):
...    print(arrangement)
...
[[1, 2], [3], [4]]
[[1, 3], [2], [4]]
[[1], [2, 3], [4]]
[[1, 4], [2], [3]]
[[1], [2, 4], [3]]
[[1], [2], [3, 4]]

To determine the number of arrangements of a set of 10 items into 5 non-empty subsets, use the s2 function:

>>> from stirling import s2
>>> s2(10, 5)
42525

MIT License

Copyright (c) Robert Smallshire

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.