The following is the example of the implementation of stadard sequence in python. Using len() and getitem method in a python class, standard sequence could be implemented.
''' --- The implementation of FrechDeck --- '''
import collections
Card = collections.namedtuple('Card', ['rank', 'suit'])
# By implementing __len__ and __getitem__, it works like a standard sequence
class FrenchDeck(object):
ranks = [str(n) for n in range(2, 11)] + list('JQKA')
suits = 'spades diamonds clubs hearts'.split()
def __init__(self):
self._cards = [Card(rank, suit) for suit in self.suits for rank in self.ranks]
def __len__(self):
return len(self._cards)
def __getitem__(self, position):
return self._cards[position]
''' --- Test --- '''
beer_card = Card('7', 'diamonds')
print beer_card #Output: Card('7', 'diamonds')
deck = FrenchDeck()
print len(deck) #Output: 52 , __len()__ of FrenchDeck invoked
# By __getitem__ method, random access is supported
from random import choice
print choice(deck)
print choice(deck)
print choice(deck)
''' Output:
Card(rank='Q', suit='spades')
Card(rank='5', suit='spades')
Card(rank='7', suit='diamonds')
'''
# By __getitem__ method, slicing supported
print deck[:3] #Output: [Card(rank='2', suit='spades'), Card(rank='3', suit='spades'), Card(rank='4', suit='spades')]
# By __getitem__ method, iteration supported
for card in deck:
print card
''' Output:
Card(rank='2', suit='spades')
Card(rank='3', suit='spades')
....
Card(rank='K', suit='hearts')
Card(rank='A', suit='hearts')
'''
for card in reversed(deck):
print card
''' Output:
Card(rank='A', suit='hearts')
Card(rank='K', suit='hearts')
...
Card(rank='3', suit='spades')
Card(rank='2', suit='spades')
'''
print Card('Q', 'diamonds') in deck #Output: True
print Card('Q', 'beasts') in deck #Output: False
# By __getitem__, sort() supported
suit_values = dict(spades=3, hearts=2, diamonds=1, clubs=0)
def rank_high(card):
rank_value = FrenchDeck.ranks.index(card.rank) # rank_value: 2, 3, 4 ... J Q K A
return rank_value * len(suit_values) + suit_values[card.suit] # rank_value has bigger weight than card.suit
for card in sorted(deck, key=rank_high): #Lowest key is first
print card
''' Output:
Card(rank='2', suit='clubs')
Card(rank='2', suit='diamonds')
...
Card(rank='A', suit='hearts')
Card(rank='A', suit='spades')
'''
for card in sorted(deck, key=rank_high, reverse=True):
print card
''' Output:
Card(rank='A', suit='spades')
Card(rank='A', suit='hearts')
...
Card(rank='2', suit='diamonds')
Card(rank='2', suit='clubs')
'''