I’ve said it once, and I’ll say it again: in Python you can do some amazing things with little or no code at all.  Sorting is also one of those things.

In poking around online, I found this little beauty that somebody had done to show how compact, elegant, and still powerfully fast one can write a Quicksort algorithm in Python:

def qsort(L):
    """
    Porting the Erlang quicksort implementation from
    http://en.wikipedia.org/wiki/Erlang_(programming_language)
    """
    if not L: return L
    Pivot, Tail = L[0], L[1:]
    return qsort([X for X in Tail if X < Pivot]) + [Pivot] + qsort([X for X in Tail if X >= Pivot])

Remembering back to the days of learning sorting algorithms, I recall that Quicksort was considered (at the time) one of the fastest, due in no small part to its recursive nature.  It was also the bane of many an entry-level Computer Science student just digging in and getting a fuse blown out learning just what recursion meant.  I even find myself going back every so often to see how rusty I’ve become with these fundamental concepts.

Looking at it now, it’s as much a piece of art as it is functional, working code.

Special thanks to the anonymous coder that put this up on Pastie.org.  Link to original.