Adding 'indirect_sort' to boost::algorithm

From: Marshall Clow (mclow.lists_at_[hidden])
Date: 2023-06-15 01:42:16

At Boostcon last month, there was a discussion of indirect sorting algorithms to boost::algorithm.

An “Indirect sort” (called 'argsort' in numpy - https://numpy.org/doc/stable/reference/generated/numpy.argsort.html) returns a sequence of indices into the collection describing how the collection can be rearranged in order to become sorted.

So I created https://github.com/boostorg/algorithm/pull/117 to start down this road.
(There’s clearly more that could be done here - stable_sort, partial_sort, nth_element, etc)

Comments welcomed.

— Marshall