how to efficiently get the k bigger elements of a list in python

Question

What´s the most efficient, elegant and pythonic way of solving this problem?

Given a list (or set or whatever) of n elements, we want to get the k biggest ones. ( Yo

Answer 1

The simple, O(n log n) way is to sort the list then get the last k elements.

The proper way is to use a selection algorithm, which runs in O(n + k log k) time.

Also, heapq.nlargest takes O(k log n) time on average, which may or may not be good enough.

(If k = O(n), then all 3 algorithms have the same complexity (i.e. don't bother). If k = O(log n), then the selection algorithm as described in Wikipedia is O(n) and heapq.nlargest is O(n log log n), but double logarithm is "constant enough" for most practical n that it doesn't matter.)