On Wed, 02 May 2007 06:10:54 +0000, Tim Roberts wrote: > Michael Hoffman <[EMAIL PROTECTED]> wrote: >> >>Hint: if you find yourself using a decorate-sort-undecorate pattern, >>sorted(key=func) or sequence.sort(key=func) might be a better idea. > > Is it? I thought I remember reading on this very list some years ago that > the performance of sequence.sort became much, much worse when a key > function was supplied.
You're probably thinking of a comparison function: sequence.sort(cmp=lambda x, y: cmp(y, x)) is a slow way of sorting a sequence in reverse order. The fast way is the two liner: sequence.sort() sequence.reverse() Faster(?) still is: sequence.sort(reverse=True) > I've tended to favor the "Schwarzian transform" (decorate-sort-undecorate) > because of that. That's what the key= argument does. cmp= is slow because the comparison function is called for EVERY comparison. The key= function is only called once per element. -- Steven D'Aprano -- http://mail.python.org/mailman/listinfo/python-list
