Simple questions on use of objects (probably faq)

James Stroud jstroud at
Wed Mar 8 21:35:48 CET 2006

Brian Elmegaard wrote:
> "Matt Hammond" <matt.hammond at> writes:
>>y_max = max([e.x for e in y])
> Would there be a way to refer back to the e with maximum x, or how
> could I find other attributes of it?

You should look into __cmp__ and other magic methods. This is probably 
the type of functionality you seem to be after.

class C:
   def __init__(self, x):
     self.x = x
   def __repr__(self):
     idnum = str(id(self))[-4:]             #
     return "C(x=%s):%s" % (self.x, idnum)  # for demo
   def __cmp__(self, other):
     return self.x - other.x

# demonstration
import random
sees = [C(x) for x in (4,7,1,3,0,9,2)]  # random-ish ints
print sees
print max(sees)
print sees


James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

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