On 22 Sep, 04:05, josh logan <[EMAIL PROTECTED]> wrote:
> Hello,
>
> I have 2 questions. Say I have this class:
>
> class Player(object):
> def __init__(self, fname, lname, score):
> self.score = score
> self.fname = fname
> self.lname = lname
> def __cmp__(self, other):
> return (-cmp(self.score, other.score) or
> cmp(self.lname, other.lname) or
> cmp(self.fname, other.fname))
> def __repr__(self):
> return 'Player(fname={0.fname}, lname={0.lname},
> score={0.score})'.format(self)
> def __eq__(self, others):
> if isinstance(other, Player):
> return (self.score == other.score and
> self.lname == other.lname and
> self.fname == other.fname)
> return False
> def __ne__(self, others):
> return not self.__eq__(others)
>
> fnames = ['Julie', 'Ben', 'Jason', 'David']
> lnames = ['Parks', 'Smith']
> scores = [100, 95, 95, 130, 58, 74]
>
> import itertools as it
>
> score_iter = it.cycle(scores)
>
> P = [Player(fn, ln, next(score_iter)) for fn in fnames for ln in
> lnames]
>
> cmp(P[0], P[1]) # returns -1
>
> sorted(P) # throws TypeError: unorderable types Player() < Player()
>
> The sorted function works when I define __lt__.
> I must be misreading the documentation, because I read for the
> documentation __cmp__ that it is called if none of the other rich
> comparison functions are defined.
> Is this a bug in Python 3.0rc1, or am I missing something?
>
> Secondly, say that we suddenly need another sorting order, where we
> want to sort by decreasing score and then by DECREASING last name
> (instead of increasing last name, defined above). Now that the
> comparison function argument is taken away from the sorted builtin,
> how do we accomplish this with the "key" parameter?
>
> Thank you
I don't know about __cmp__ but for the second part of the question you
can probably do:
sorted(P, key=lambda p: (p.score, p.lname), reverse=True)
HTH
--
Arnaud
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