流畅的python，Fluent Python 第一章笔记
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import collections
Card = collections.namedtuple('Card', 'rank suit')
class Frenchdeck:
ranks = [str(n) for n in range(2, 11)] + list('JQKA') # 把牌的数字与花色赋值给类属性
suits = 'spades diamonds clubs hearts'.split()
def __init__(self): # 用列表生成式制作一副牌
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, item): # 定义这个[]取值会用到。
return self._cards[item]
def __repr__(self):
return f'{self._cards!r}'
deck = Frenchdeck()
print(deck)
print(len(deck))
print(deck[0])
print(deck[1:3])
from random import choice
print(choice(deck)) # 随机算一张牌
print()
# 最后通过通过一个自定义的函数对纸牌进行排序
suit_values = dict(spades=3, hearts=2, diamonds=1,clubs=0) # 定义一个花色的数值
def spades_high(card):
rank_value = Frenchdeck.ranks.index(card.rank) # 对纸牌的位置进行取值
return rank_value * len(suit_values) + suit_values[card.suit] # 返回每张牌对应的数值
for card in sorted(deck, key=spades_high):
print(card)
/usr/local/bin/python3.7 /Users/shijianzhong/study/Fluent_Python/第一章/t1.1.py [Card(rank='2', suit='spades'), Card(rank='2', suit='diamonds'), Card(rank='2', suit='clubs'), Card(rank='2', suit='hearts'), Card(rank='3', suit='spades'), Card(rank='3', suit='diamonds'), Card(rank='3', suit='clubs'), Card(rank='3', suit='hearts'), Card(rank='4', suit='spades'), Card(rank='4', suit='diamonds'), Card(rank='4', suit='clubs'), Card(rank='4', suit='hearts'), Card(rank='5', suit='spades'), Card(rank='5', suit='diamonds'), Card(rank='5', suit='clubs'), Card(rank='5', suit='hearts'), Card(rank='6', suit='spades'), Card(rank='6', suit='diamonds'), Card(rank='6', suit='clubs'), Card(rank='6', suit='hearts'), Card(rank='7', suit='spades'), Card(rank='7', suit='diamonds'), Card(rank='7', suit='clubs'), Card(rank='7', suit='hearts'), Card(rank='8', suit='spades'), Card(rank='8', suit='diamonds'), Card(rank='8', suit='clubs'), Card(rank='8', suit='hearts'), Card(rank='9', suit='spades'), Card(rank='9', suit='diamonds'), Card(rank='9', suit='clubs'), Card(rank='9', suit='hearts'), Card(rank='10', suit='spades'), Card(rank='10', suit='diamonds'), Card(rank='10', suit='clubs'), Card(rank='10', suit='hearts'), Card(rank='J', suit='spades'), Card(rank='J', suit='diamonds'), Card(rank='J', suit='clubs'), Card(rank='J', suit='hearts'), Card(rank='Q', suit='spades'), Card(rank='Q', suit='diamonds'), Card(rank='Q', suit='clubs'), Card(rank='Q', suit='hearts'), Card(rank='K', suit='spades'), Card(rank='K', suit='diamonds'), Card(rank='K', suit='clubs'), Card(rank='K', suit='hearts'), Card(rank='A', suit='spades'), Card(rank='A', suit='diamonds'), Card(rank='A', suit='clubs'), Card(rank='A', suit='hearts')] 52 Card(rank='2', suit='spades') [Card(rank='2', suit='diamonds'), Card(rank='2', suit='clubs')] Card(rank='3', suit='hearts') Card(rank='2', suit='clubs') Card(rank='2', suit='diamonds') Card(rank='2', suit='hearts') Card(rank='2', suit='spades') Card(rank='3', suit='clubs') Card(rank='3', suit='diamonds') Card(rank='3', suit='hearts') Card(rank='3', suit='spades') Card(rank='4', suit='clubs') Card(rank='4', suit='diamonds') Card(rank='4', suit='hearts') Card(rank='4', suit='spades') Card(rank='5', suit='clubs') Card(rank='5', suit='diamonds') Card(rank='5', suit='hearts') Card(rank='5', suit='spades') Card(rank='6', suit='clubs') Card(rank='6', suit='diamonds') Card(rank='6', suit='hearts') Card(rank='6', suit='spades') Card(rank='7', suit='clubs') Card(rank='7', suit='diamonds') Card(rank='7', suit='hearts') Card(rank='7', suit='spades') Card(rank='8', suit='clubs') Card(rank='8', suit='diamonds') Card(rank='8', suit='hearts') Card(rank='8', suit='spades') Card(rank='9', suit='clubs') Card(rank='9', suit='diamonds') Card(rank='9', suit='hearts') Card(rank='9', suit='spades') Card(rank='10', suit='clubs') Card(rank='10', suit='diamonds') Card(rank='10', suit='hearts') Card(rank='10', suit='spades') Card(rank='J', suit='clubs') Card(rank='J', suit='diamonds') Card(rank='J', suit='hearts') Card(rank='J', suit='spades') Card(rank='Q', suit='clubs') Card(rank='Q', suit='diamonds') Card(rank='Q', suit='hearts') Card(rank='Q', suit='spades') Card(rank='K', suit='clubs') Card(rank='K', suit='diamonds') Card(rank='K', suit='hearts') Card(rank='K', suit='spades') Card(rank='A', suit='clubs') Card(rank='A', suit='diamonds') Card(rank='A', suit='hearts') Card(rank='A', suit='spades') Process finished with exit code 0
我不知道第一章，第一节就上这么难，反正我是觉的第一次看完全看不懂，现在看算还好，但也要花点脑子。
1.2如何使用特殊方法。
len调用的是__len__，对list,str,bytearray会直接返回PyVarObject的ob_size属性。
from math import hypot
class Vector:
def __init__(self, x=0, y=0):
self.x = x
self.y = y
def __repr__(self): # 强制repr格式化输出更好
return 'Vector(%r, %r)' % (self.x, self.y)
def __abs__(self):
return hypot(self.x, self.y)
def __bool__(self):
return bool(abs(self))
def __add__(self, other):
x = self.x + other.x
y = self.y + other.y
return Vector(x, y)
def __mul__(self, other):
return Vector(self.x * other, self.y * other)
wrong = Vector('1,','2')
true = Vector(1, 2)
print(wrong)
print(true)
print(true * 3)
print(bool(true))
print(abs(true))
/usr/local/bin/python3.7 /Users/shijianzhong/study/Fluent_Python/第一章/t1-2.py
Vector('1,', '2')
Vector(1, 2)
Vector(3, 6)
True
2.23606797749979
Process finished with exit code 0
1.2.4自定义的布尔值
对一个对象查找bool值，首相调用对象的__bool__方法返回的结果，如没有__bool__就找__len__返回的是否为0，
如果两个方法都没有，返回的就是True
1.3 特殊方法一览
Python中的83个特殊方法的名字，其中43个用于实现算数运算，位运算和比较操作。
跟运算符无关的特殊方法
字符串/字节序列表示转换 __repr__ __str__ __format__ __bytes__
数值转化 __abs__ __bool__ __complex__ __int__ __float__ __hash__ __index__
集合模拟 __len__ __getitem__ __setitem__ __delitem__ __contains__ __missing__(字典可用)
迭代枚举 __iter__ __reversed__ __next__
可调用模拟 __call__
上下文管理 __enter__ __exit__
实例的创建与销毁 __new__ __init__ __del__
属性管理 __getattr__ __getattribute__ __setattr__ __delattr__ __dir__
属性描述符 __get__ __set__ __delete__
跟类相关的服务 __prepare__ __instancecheck__ __subclasscheck__
跟运算符相关的特殊方法
一元操作符 __neg__ - __pos__ + __abs__ abs()
比较运算符 __lt__ < __le__ <= __eq__ == __ne__ != __ge__>= __gt__>
算数运算符 __add__ + __sub__ - __mul__ * __truediv__ / __floordiv__ // __mod__% __divmod__divmod() __pow__**或pow() __round__round()
算数运算符
增量赋值运算符
位运算符
反向位运算符
增量赋值位远算符
后下面这些不写了，在书P11都有。
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