Namedtuples problem

[Deborah Swanson]

Thanks all of you for replying.

I'm going to have to study your responses a bit before I can respond. I
wrote this code the way I did because I was getting errors that I
stopped getting with these fixes and I got the correct results from this
code, up until the last line. All of you introduced concepts that I
haven't seen or thought of before and I'll need to look at them
carefully.

Peter's right about pandas and we talked about this the first time we
visited this problem. pandas is a steep learning curve, and it makes
more sense to stick with straight Python this first time.  This
spreadsheet problem is fairly typical of several I need to do, and I
will be using pandas for future problems. But this time I'll stick with
learning and understanding what I've got.

Thanks again all, and I'll write back when I have a handle on what
you've said, and probably I'll have more questions to ask.