Python, how to sort list of object? [duplicate]

Answer 1

The idea is still the same. Just that you will be looking for a specific attribute in the class object.

For your card class, you could do something like this:

hand = [ Card(10, 'H'), Card(2,'h'), Card(12,'h'), Card(13, 'h'), Card(14, 'h') ]

Then you could do

sorted_cards = sorted(hand, key=lambda x: x.rank)

The output looks something like this:

>>> [card.number for card in sorted_cards]
[2, 10, 12, 13, 14]

Answer 2

This is the object-oriented approach. At a minimum, you should specify __eq__ and __lt__ operations for this to work. Then just use sorted(hand).

class Card(object):

    def __init__(self, rank, suit):
        self.rank = rank
        self.suit = suit

    def __eq__(self, other):
        return self.rank == other.rank and self.suit == other.suit

    def __lt__(self, other):
        return self.rank < other.rank

hand = [Card(10, 'H'), Card(2, 'h'), Card(12, 'h'), Card(13, 'h'), Card(14, 'h')]
hand_order = [c.rank for c in hand]  # [10, 2, 12, 13, 14]

hand_sorted = sorted(hand)
hand_sorted_order = [c.rank for c in hand_sorted]  # [2, 10, 12, 13, 14]

It's good practice to make object sorting logic, if applicable, a property of the class rather than incorporated in each instance the ordering is required. This way you can just call sorted(list_of_objects) each time.