i have not been following this discussion in detail, so someone may have already explained this, but it should not be necessary to actually construct the roulette wheel to select values from it. what you are doing is selecting from a list where the there are different probabilities of selecting different entries. i am pretty sure that can be done more efficiently than by constructing a new list with many more entries whose aim is to simulate that (which is what the roulette wheel seems to be in your code, if i have understood correctly).
more precisely, i think you can adapt the trick used to select a line at random from a file by scanning the file just once. sorry if i have misunderstood, andrew -- http://mail.python.org/mailman/listinfo/python-list
