Implement a median / select nth algorithm.

[GuillaumeDIDIER]

I need to find Q1, Q3 and the median on large containers, and parallel sorting doesn't exactly scale.

I am wondering if it would be possible to extend rayon to also have the median of median algorithm to find medians and a selection of the k-th smallest / largest element (which is the generalised primitive needed to implement most median / quartiles definitions)

(Or if there is now way of implementing this effectively to leverage parallelism)

If that would make sense, I'd be willing to work on the implementation of it and submit a PR.

[cuviper]

I don't know how to implement that parallel algorithm off-hand, but it may be possible.