类的相关介绍 """ class Human(object): phylum = 'Chordata' order = 'Primates' family = 'Human Being' ZhangSan = Human() """ # 已将该实例的属性值重新定义，不会受到此后类属性值变化的影响 """ ZhangSan.family =
- 类的相关介绍
class Human(object):
phylum = 'Chordata'
order = 'Primates'
family = 'Human Being'
ZhangSan = Human()
"""
# 已将该实例的属性值重新定义，不会受到此后类属性值变化的影响
"""
ZhangSan.family = 'Mankind'
print(ZhangSan.family) # Mankind
# 类属性也是可以修改的
Human.family = 'Homo'
print(ZhangSan.family)# Mankind
Lily = Human()
print(Lily.family)# Homo
ZhangSan.kingdom = 'Animalia'#实例的属性可以直接添加，类的属性也是如此
"""
"""
class Human(object):
domain = 'eukarya'
def __init__(self, kingdom='Animalia', phylum='Chordata',
order='Primates', family='Human Being'):
self.kingdom = kingdom
self.phylum = phylum
self.order = order
self.family = family
# 实例方法
# def 中都要包含self
def typewrite(self):
print("This is %s typing words!" %(self.family))
def add(self, n1, n2):
n = n1 + n2
print(str(n1) + '+' + str(n2) + '=' + str(n))
print('You see! %s can calculate!' %(self.family))
ZhangSan = Human()
LiSi = Human(kingdom='Animal', family='Homo')
print(LiSi.kingdom)
print(LiSi.family)
print(ZhangSan.kingdom)
"""
"""
class Human(object):
domain = 'eukarya'
def __init__(self, kingdom='Animalia', phylum='Chordata',
order='Primates', family='Human Being'):
self.kingdom = kingdom
self.phylum = phylum
self.order = order
self.family = family
def typewrite(self):
print("This is %s typing words!" %(self.family))
def add(self, n1, n2):
n = n1 + n2
print(str(n1) + '+' + str(n2) + '=' + str(n))
print('You see! %s can calculate!' %(self.family))
# 类方法
# 第一个参数为cls，表示类本身
# 定义类方法时，使用@classmethod 装饰器
@classmethod
def showclassmethodinfo(cls):
print(cls.__name__) # __name__属性，其值为名
print(dir(cls)) # 展示本类的所有方法
ZhangSan = Human()
print(ZhangSan.showclassmethodinfo())
print(Human.showclassmethodinfo())
"""
"""
Human
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'add', 'domain', 'showclassmethodinfo', 'typewrite']
None
Human
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'add', 'domain', 'showclassmethodinfo', 'typewrite']
None
"""
"""
"""
"""
class Human(object):
domain = 'eukarya' # 类属性（可通过类名，实例访问）
def __init__(self, kingdom='Animalia', phylum='Chordata',
order='Primates', family='Human Being'):
self.kingdom = kingdom # 实例属性（只能通过实例访问）
self.phylum = phylum
self.order = order
self.family = family
def typewrite(self):
print("This is %s typing words!" %(self.family))
def add(self, n1, n2):
n = n1 + n2
print(str(n1) + '+' + str(n2) + '=' + str(n))
print('You see! %s can calculate!' %(self.family))
@classmethod
def showclassmethodinfo(cls):
print(cls.__name__)
print(dir(cls))
# 静态方法
# 无参数
# 定义类方法时，使用@staticmethod 装饰器
@staticmethod
def showclassattributeinfo():
print(Human.__dict__) # __dict__属性，返回键名为属性名，键值为属性值的字典
# 双下划线前后缀的属性为自带的特殊的类属性
ZhangSan = Human()
print(ZhangSan.showclassattributeinfo())
print(Human.showclassattributeinfo())
"""
class Human(object):
domain = 'eukarya' # 类属性（可通过类名，实例访问）
def __init__(self, kingdom='Animalia', phylum='Chordata',
order='Primates', family='Human Being'):
self.kingdom = kingdom # 实例属性（只能通过实例访问）
self.phylum = phylum
self.__order = order # 私有属性
self.family = family
def typewrite(self):
print("This is %s typing words!" %(self.family))
def add(self, n1, n2):
n = n1 + n2
print(str(n1) + '+' + str(n2) + '=' + str(n))
print('You see! %s can calculate!' %(self.family))
@classmethod
def showclassmethodinfo(cls):
print(cls.__name__)
print(dir(cls))
@staticmethod
def showclassattributeinfo():
print(Human.__dict__)
"""
ZhangSan = Human()
print(ZhangSan._Human__order) # Primates
print(ZhangSan.order) #与ZhanSan.__order结果相同，错误
"""
# 隐式继承
# 完全继承所有成员
# 隐式继承中，父类的私有成员不能继承
# 如果在子类中使用__init__来构造实例属性时，一定要用super函数去初始化父类
class Male(Human):
def __init__(self, gender='male'):
super(Male, self).__init__()# super函数的第一个参数是父类的名字
self.gender = gender
def add(self, n1, n2):
# 在子类中重新定义add方法
n = n1 - n2
print(str(n1) + '-' + str(n2) + '=' + str(n))
print('You see! %s can NOT use addition!' %(self.gender))
someoneismale = Male()
print(someoneismale.family)# Human Being
print(someoneismale.kingdom)# Animalia
print(someoneismale.add(1, 1))
# 父类的实例与子类不是同一个类型
# 子类的实例与父类是同类
# 继承与同一个父类的子类是不同类
# 调用对象的add方法
def addition(obj, n1, n2):
obj.add(n1, n2)
addition(someoneismale, 1, 1)
addition(Male(), 1, 1)
- 说明文档格式
"""
Precondition: item is in self. 先验条件（只有该语句为真的时候，方法才能够正确地执行操作）
Raises: KeyError if item in not in self. 用来说明可能发生的异常，通常是无法满足方法的先验条件而导致的结果
Postcondition: item is removed from self. 后验条件（当方法执行完毕后，变为了什么情况）
"""
- 解包
>>> a
'j'
>>> b
'k'
>>> c
'l'
>>> a, b, c = ['j', 'k', (1, 2, 3)]
>>> a
'j'
>>> b
'k'
>>> c
(1, 2, 3)
>>> record = ('Dave', 'dave@example.com', '773-555-1212', '847-555-1212')
>>> name, email, *phone_numbers = record
>>> name
'Dave'
'dave@example.com'
>>> phone_numbers
['773-555-1212', '847-555-1212']
>>> *trailing, current = [10, 8, 7, 1, 9, 5, 10, 3]
>>> trailing
[10, 8, 7, 1, 9, 5, 10]
>>> current
3
>>> record = ('ACME', 50, 123.45, (12, 18, 2012))
>>> name, *_, (*_, year) = record
>>> name
'ACME'
>>> year
2012
- 堆
q = deque(maxlen=3)
q.append(3)
q.appendleft(3)
q.pop()
q.popleft()
>>> import heapq
>>> nums = [1, 8, 2, 23, 7, -4, 18, 23, 42, 37, 2]
>>> print(heapq.nlargest(2, nums))
[42, 37]
>>> print(heapq.nsmallest(2, nums))
[-4, 1]
import heapq
portfolio = [
{'name':'IBM', 'shares':100, 'price':91.1},
{'name':'AAPL', 'shares':50, 'price':543.22},
{'name':'FB', 'shares':200, 'price':21.09},
{'name':'HPQ', 'shares':35, 'price':31.75},
{'name':'YHOO', 'shares':45, 'price':16.35},
{'name':'ACME', 'shares':75, 'price':115.65}
]
cheap = heapq.nsmallest(3, portfolio, key=lambda s: s['price'])
expensive = heapq.nlargest(3, portfolio, key=lambda s: s['price'])
print(cheap, '\n', expensive)
"""
[{'shares': 45, 'name': 'YHOO', 'price': 16.35}, {'shares': 200, 'name': 'FB', 'price': 21.09}, {'shares': 35, 'name': 'HPQ', 'price': 31.75}]
[{'shares': 50, 'name': 'AAPL', 'price': 543.22}, {'shares': 75, 'name': 'ACME', 'price': 115.65}, {'shares': 100, 'name': 'IBM', 'price': 91.1}]
"""
# 优先级队列的实现
import heapq
class PriorityQueue:
def __init__(self):
self._queue = []
self._index = 0
def push(self, item, priority):
heapq.heappush(self._queue, (-priority, self._index, item))
self._index += 1
def pop(self):
return heapq.heappop(self._queue)[-1]
# 如何使用
class Item:
def __init__(self, name):
self.name = name
def __repr__(self):
return 'Item({!r})'.format(self.name)
q= PriorityQueue()
q.push(Item('foo'), 1)
q.push(Item('bar'), 5)
q.push(Item('spam'), 4)
q.push(Item('grok'), 1)
for i in range(4):
print(q.pop())
"""
Item('bar')
Item('spam')
Item('foo')
Item('grok')
"""
- 特殊变量
_xxx 不能用 from module import* 导入
xxx 系统定义名字
__xxx 类中私有变量名