efficient partial sort in Python ?

[Chiu Hsiang Hsu]

I know that Python use Timsort as default sorting algorithm and it is efficient,
but I just wanna have a partial sorting (n-largest/smallest elements).

In the current state, I can only find this kind of functions from heapq,
but it's too slow for this problem,
the pure c sorted function can easily beat heapq.nlargest even though it sort all the elements.

I think it would be better if we have an effeicient partial sorting function,
maybe it could be like this : partial_sorted(data, n), data.partial_sort(n)

Does anyone have any more information for partial sorting ?

Btw, C++ has a partial_sort function in <algorithm>, but I don't know what algorithm it really use.