1、扑克牌
import collections
Card = collections.namedtuple('Card',['rank','suit'])
class Frenchdeck:
ranks = [str(i) for i in range(2,11)]+list('JQKA')
suits = ['黑桃','红心','梅花','方块']
def __init__(self):
self._cards=[Card(rank,suit) for rank in self.ranks for suit in self.suits]
def __len__(self):
return len(self._cards)
def __getitem__(self,position):
return self._cards[position]
suit_values={'黑桃':3,'红心':2,'梅花':1,'方块':0}
deck=Frenchdeck()
def cards_values(card):
rank_value=Frenchdeck.ranks.index(card.rank)
return rank_value*len(suit_values)+suit_values[card.suit]
for card in sorted(deck,key=cards_values,reverse=True):
print (card)
2、以上collection,sorted需注意。
sorted(iteration,key=Function)
Function 返回一个值作为比较依据
3、Special method，also called magic method or dunder method.
图片.png
图片.png
4、自定义向量类型
class Vector:
def __init__(self,x=0,y=0):
self.x=x
self.y=y
def __add__(self,other):
x=self.x+other.x
y=self.y+other.y
return Vector(x ,y)
def __abs__(self):
return self.x+self.y
def __repr__(self):
return 'Vector(%r,%r)'% (self.x , self.y)
5 、why len() not .len?
len()直接调用基于C的内置方法而不是自定义方法，但是通过对len的定义又可以自定义某个类的len()，从而在效率和可更改性上达到平衡，而且一统的模式更加符合美学，即Zen of Python.