Thanks to everyone who posted. First, I don't think my question was clear enough: Rob Cowie, Ant, Simon Forman, [EMAIL PROTECTED], and Jon Ribbens offered solutions that don't quite work as-is, because I need multiple values to map to a single type. Tim Chase and Bruno Destuilliers both offer very nice OOP solutions, and I think this is the route I will probably go. However, for the simplest and easiest solution, I really like this from Peter Otten: inflated = [0]*5 groups = [[0,1,3],[4],[2]] for value in [1,1,0,4]: inflated[value] += 1 print [sum(inflated[i] for i in group) for group in groups]
4 lines (one more to assign the lists to name values, but that's minor), and intuitive. If I had just thought of this to begin with, I wouldn't have bothered posting. Thanks to all for the advice. THN -- http://mail.python.org/mailman/listinfo/python-list