sordted()は安定ソート

安定ソートか確認

import random
import operator

def test_list_sort():
    class Person(object):
        def __init__(self, name, age):
            self.name = name
            self.age = age
        def __repr__(self):
            return repr((self.name, self.age))

    persons = []
    for n in range(10):
        persons.append(
            Person('name%05d' % n, random.randint(1, 3))
        )

    result = sorted(persons, key = operator.attrgetter('age'))

    for person in result:
        print person

if __name__ == '__main__':
    test_list_sort()

('name00002', 1)
('name00005', 1)
('name00007', 1)
('name00000', 2)
('name00003', 2)
('name00004', 2)
('name00001', 3)
('name00006', 3)
('name00008', 3)
('name00009', 3)

確かに。