Question

How can use the key argument for the min function to compare a list of objects’s 1 attribute?

Example

class SpecialNumber:
    def __init__(self, i):
        self.number = i

li = [SpecialNumber(1), SpecialNumber(3), SpecialNumber(2)]

Answer 1

http://docs.python.org/library/operator.html#operator.attrgetter

from operator import attrgetter
min_num = min(li,key=attrgetter('number'))

Sample interactive session:

>>> li = [SpecialNumber(1), SpecialNumber(3), SpecialNumber(2)]
>>> [i.number for i in li]
[1, 3, 2]
>>> min_num = min(li,key=attrgetter('number'))
>>> print min_num.number
1