# 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
```