[Tutor] Sorting

[Kalle Svensson]

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[Timothy M. Brauch]
> I would like to be able to sort the list of Participants in
> Competition in specific ways.  I am pretty sure it can be done with
> sort(cmpfunc), but I can't figure it out and documention on the
> cmpfunc for sort seems to be lacking, or hard to find.  Here is an
> example session of what I would like to have.
[snip]

Maybe simple compare functions like these would work?

  def compare_by_team(x, y):
      return cmp(x.team, y.team)

  def compare_by_name(x, y):
      return (cmp(x.last_name, y.last_name) or
              cmp(x.first_name, y.first_name))

They mostly use the builtin function cmp that is the standard compare
function.  lst.sort() and lst.sort(cmp) are equivalent.

compare_by_name is a bit clever with the or.  It could be written as

  def compare_by_name(x, y):
      ln = cmp(x.last_name, y.last_name)
      if not ln: # Last names are equal
          return cmp(x.first_name, y.first_name)
      return ln

which is perhaps more clear.

> I tried writing sort_by_team() by scratch using if statements, but
> somehow there is an error in my statements and possibly my identing,
> but at something like 15 lines to sort a list, I think I am on the
> wrong track.  So, I would greatly appreciate it if someone could
> help me with the sort().

Generally, if you post more of your code and error messages, it is
easier to help.  This time, I don't think that it mattered.  Just a
tip for the future.

Peace,
  Kalle
- -- 
Kalle Svensson, http://www.juckapan.org/~kalle/
Student, root and saint in the Church of Emacs.
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