I've been looking at some of the suggested approaches and looked a little at Michael's bit which works well.... bisect is a module i always struggle with (hee hee)
I am intrigued by Ben's solution and Ben's distilled my problem quite nicely, but, well....i don't understand what "point" is doing with wieght for key, weight for zlist, furthermore, it barfs in my interpreter... (Python 2.3) -- http://mail.python.org/mailman/listinfo/python-list