Feature request: intersection and union of lists of ranges

[n1ngu]

Let a range be a pair of sortable objects, e.g. a tuple of numbers, strings, date objects or anything implementing the __lt__ family operators (or maybe a sorting key function should be accepted in the mood of the sorted builtin!)

Given an iterable of ranges, I find myself rewriting functions to compute the intersection (usually of 2 ranges) and the union of those.

For example

>>> ranges = [(1,5), (2,6), (1,4)]
>>> intersection(ranges)
(2, 4)
>>> union(ranges)
[(1,6)]
>>> ranges = [(1,5), (6,8), (7,9)]
>>> intersection(ranges)
None
>>> union(ranges)
[(1,5),(6,9)]

Input data might be not necessarily ordered.

E.g see https://stackoverflow.com/questions/52073609/get-unions-and-intersections-of-list-of-datetime-ranges-python

I think the boltons library should have a place for functions of this kind!

[kadarakos]

The very general structure for this I think is the Interval Tree right? https://en.wikipedia.org/wiki/Interval_tree