Python自动化开发课堂笔记【Day04】 - Python基础（函数）

1 def foo():
2     print(‘from foo‘)
3 func=foo
4 print(foo) ---> <function foo at 0x00386C48> --> foo函数在内存中地址
5 print(func) ---> <function foo at 0x00386C48>
6 foo() ---> from foo
7 func() ---> from foo

1 def foo():
2     print(‘from foo‘)
3 def bar(func):
4     print(func) ---> <function foo at 0x00306DF8> --> func函数在内存中地址
5     func() ---> from foo
6 bar(foo)

1 def foo():
2     print(‘from foo‘)
3 def bar(func):
4     return func ---> 作为返回值
5 f=bar(foo)
6 print(f) ---> <function foo at 0x002E6DF8>
7 f() ---> from foo

1 def foo():
2     print(‘from foo‘)
3 dic={‘func‘:foo} ---> 在字典中作为键值存在
4 print(dic[‘func‘]) ---> <function foo at 0x00556C48>
5 dic[‘func‘]() ---> from foo

SQL语句操作判定
 
 1 def select(sql):
 2     print(‘========>select‘)
 3 def insert(sql):
 4     print(‘========>add‘)
 5 def delete(sql):
 6     print(‘========>delete‘)
 7 def update(sql):
 8     print(‘========>update‘)
 9 func_dic={‘select‘:select, ‘update‘:update, ‘insert‘:insert, ‘delete‘:delete}
10 def main():
11     while True:
12         sql = input(‘>>: ‘).strip()
13         if not sql:continue
14         l = sql.split()
15         cmd=l[0] ---> 读取SQL语句首单词
16         if cmd in func_dic:
17             func_dic[cmd](l) ---> 当作容器类型的元素
18 main()

简易姓名查询数据库 

 1 def init(database):
 2     database[‘first‘] = {‘Jia‘:{‘Jia Xiao Liang‘}}
 3     database[‘middle‘] = {‘Xiao‘:{‘Jia Xiao Liang‘}}
 4     database[‘last‘] = {‘Liang‘:{‘Jia Xiao Liang‘}}
 5 
 6 def lookup(database, lable, name):
 7     return  database[lable].get(name)
 8 
 9 def store(database, full_name):
10     names = full_name.split(‘ ‘)
11     if len(names) == 2:
12         names.insert(1,‘ ‘)
13     lables = ‘first‘,‘middle‘,‘last‘
14     for lable, name in zip(lables,names):
15         people = lookup(database, lable, name)
16         print(people)
17         if people:
18             database[lable][name].add(full_name)
19         else:
20             database[lable][name] = {full_name}
21 
22 if __name__ == ‘__main__‘:
23     storage = dict()
24     print(type(storage))
25     init(storage)
26     while True:
27         print(‘Store:‘,storage)
28         name = input(‘>>>‘).strip()
29         store(storage,name)

1 def max2(x,y):
2     return x if x > y else y
3 def max4(a,b,c,d):
4     res1=max2(a,b)
5     res2=max2(res1,c)
6     res3=max2(res2,d)
7     return res3
8 print(max4(10,99,31,22))

1 def f1():
2     def f2():
3         print(‘from f2‘)
4         def f3():
5             print(‘from f3‘)
6         f3()
7     f2()
8 f1()

1 print(sum) ---> <built-in function sum>
2 print(max) ---> <built-in function sum>
3 print(min) ---> <built-in function sum>
4 import builtins 
5 for i in dir(builtins):
6     print(i) ---> 打印出所有内置函数

1 x=1
2 def func():
3     money=2000 ---> 局部名称空间中的变量
4     x=2
5     print(‘func x = ‘, x)
6 print(x)
7 print(func)
8 func()
9 # print(money) ---> 报错，money是函数中定义的变量，属于局部名称空间

 变量名字的查找顺序：局部命名空间 ---> 全局命名空间 ---> 内置命名空间
 1 x=1 ---> 属于全局作用域，内部函数也可以调用
 2 def func():
 3     x=2 ---> 函数内变量属于局部作用域，函数外部不可调用
 4     print(‘local.x = ‘,x) ---> x = 2
 5     sum=123123
 6     print(‘local.sum = ‘,sum) ---> sum = 123123
 7     print(globals()) ---> {‘__doc__‘: None, ‘__cached__‘: None, ‘__package__‘: None, ‘func‘: <function func at 0x00456C48>, ‘__loader__‘: <_frozen_importlib_external.SourceFileLoader object at 0x00415AB0>, ‘__spec__‘: None, ‘__file__‘: ‘C:/Users/ajiax/PycharmProjects/Python17/Day04/fortest.py‘, ‘__builtins__‘: <module ‘builtins‘ (built-in)>, ‘x‘: 1, ‘__name__‘: ‘__main__‘}
 8     print(locals()) ---> {‘x‘: 2, ‘sum‘: 123123}
 9     print(globals() is locals()) ---> False
10 func()
11 print(‘global.x = ‘,x)
12 print(globals()) ---> {‘__doc__‘: None, ‘__cached__‘: None, ‘__package__‘: None, ‘func‘: <function func at 0x00456C48>, ‘__loader__‘: <_frozen_importlib_external.SourceFileLoader object at 0x00415AB0>, ‘__spec__‘: None, ‘__file__‘: ‘C:/Users/ajiax/PycharmProjects/Python17/Day04/fortest.py‘, ‘__builtins__‘: <module ‘builtins‘ (built-in)>, ‘x‘: 1, ‘__name__‘: ‘__main__‘}
13 print(locals()) ---> {‘__doc__‘: None, ‘__cached__‘: None, ‘__package__‘: None, ‘func‘: <function func at 0x00456C48>, ‘__loader__‘: <_frozen_importlib_external.SourceFileLoader object at 0x00415AB0>, ‘__spec__‘: None, ‘__file__‘: ‘C:/Users/ajiax/PycharmProjects/Python17/Day04/fortest.py‘, ‘__builtins__‘: <module ‘builtins‘ (built-in)>, ‘x‘: 1, ‘__name__‘: ‘__main__‘}
14 print(globals() is locals()) ---> True

下划线部分可以理解为一个有外部作用域形成的包裹，并将函数f2()包裹在里面，从而形成闭包函数
1 x = 11 ---> 全局作用域变量，闭包函数无法调用
2 def f1():
3     x = 1 ---> 外部作用域的变量，闭包函数可以调用
4     def f2(): ---> 闭包函数
5         print(x)
6     return f2
7 f=f1()
8 print(f) ---> <function f1.<locals>.f2 at 0x002D6C48>
9 f() ---> 1 ---> 很明显结果是由闭包函数f2()调用其外部作用域的变量x的结果，而非全局变量的x

 惰性计算，爬取网页内容
1 from urllib.request import urlopen
2 
3 def index(url):
4     def get():
5         return urlopen(url).read().decode(‘utf-8‘) ---> 将从网页上爬取下来的内容由字节形式转化为urf-8
6     return get
7 web = index(input(‘>>>‘)) ---> 输入需要爬取的网页地址
8 print(web()) ---> 打印爬取到的网页内容

print(web.__closure__[0].cell_contents) ---> 将闭包函数引用的外部命名空间的变量显示出来，多个变量以元组的形式存在

 1 x=11
 2 y=22
 3 def f1():
 4     x=1
 5     y=2
 6     def f2():
 7         print(‘x = %s and y = %s‘ % (x,y))
 8     return f2
 9 f=f1()
10 f() ---> x = 1 and y = 2
11 print(f.__closure__[0].cell_contents,f.__closure__[1].cell_contents) ---> 1 2
12 print(f.__closure__) ---> (<cell at 0x00245AF0: int object at 0x66115910>, <cell at 0x00245B50: int object at 0x66115920>)

 无参数装饰器的简单实现
 1 import time
 2 def timmer(func):
 3     def wrapper():
 4         start_time=time.time()
 5         func()
 6         stop_time=time.time()
 7         print(‘run time is %s‘ %(stop_time-start_time))
 8     return wrapper
 9 @timmer #index=timmer(index)将他正下方的函数的函数名作为参数传给timer函数，固定只有一个参数，让后再讲timer函数的返回值再重新绑定给index函数
10 def index():
11     time.sleep(3)
12     print(‘welcome to index‘)
13 index() #实际上已经是wrapper() ---> 已经不是原来的index()函数，指向的内存地址为wrapper函数的内存地址

 多参数装饰器的简单实现
 1 import time
 2 def timer(func):
 3     def wrapper(*args,**kwargs):
 4         start_time=time.time()
 5         res = func(*args,**kwargs)
 6         stop_time=time.time()
 7         print(‘run time is %s‘ %(stop_time-start_time))
 8         return res
 9     return wrapper
10 @timer #index=timmer(index)将他正下方的函数作为参数传入
11 def index(name,age):
12     time.sleep(3)
13     print(‘welcome to index‘)
14     return name,age
15 res = index(‘Albert‘,30) #wrapper()
16 print(res)

 多层装饰器嵌套
 1 import time
 2 def timer(func):
 3     def wrapper(*args,**kwargs):
 4         print(‘====>timmer.wrapper‘)
 5         start_time=time.time()
 6         res=func(*args,**kwargs) #auth_wrapper
 7         stop_time=time.time()
 8         print(‘run time is %s‘ %(stop_time-start_time))
 9         return res
10     return wrapper
11 
12 login_user = {‘name‘:None,‘status‘:False}
13 def out_auth(driver = ‘file‘):
14     def auth(func):
15         def wrapper(*args,**kwargs):
16             print(‘====>auth.wrapper‘)
17             if driver == ‘file‘:
18                 if login_user[‘name‘] and login_user[‘status‘]:
19                     res = func(*args,**kwargs)
20                     return res
21                 else:
22                     name = input(‘>>>‘)
23                     psw = input(‘>>>‘)
24                     if name == ‘Albert‘ and psw ==‘123‘:
25                         login_user[‘name‘] = ‘Albert‘
26                         login_user[‘status‘] = True
27                         print(‘\033[45mlogin successful\033[0m‘)
28                         res = func(*args,**kwargs)
29                         return res
30                     else:
31                         print(‘\033[45mlogin failed\033[0m‘)
32             elif driver == ‘ldap‘:
33                 print(‘===========LDAP‘)
34             elif driver == ‘mysql‘:
35                 print(‘===========MYSQL‘)
36                 return func(*args,**kwargs)
37             else:
38                 print(‘===========N/A‘)
39         return wrapper
40     return auth
41 @timer #auth====>index=auth(index)===>index=auth_wrapper
42 @out_auth(driver=‘file‘)#@auth====>index=auth(index)===>index=auth_wrapper
43 def index():
44     print(‘Welcome to index‘)
45 @out_auth(driver=‘mysql‘)
46 def home(name):
47     print(‘%s welcome to homepage‘ % name)
48 
49 index()
50 home(‘Albert‘)

 1 只满足重复，因而不是迭代
 2 while True:
 3     print(‘====>‘)
 4     
 5 下面才为迭代
 6 l = [1, 2, 3]
 7 count = 0
 8 while count < len(l):
 9     print(‘====>‘, l[count])
10     count += 1
11 
12 l = (1, 2, 3)
13 count = 0
14 while count < len(l):
15     print(‘====>‘, l[count])
16     count += 1
17 
18 s=‘hello‘
19 count = 0
20 while count < len(s):
21     print(‘====>‘, s[count])
22     count += 1

1 dic={‘a‘:1,‘b‘:2,‘c‘:3}
2 i=dic.__iter__()
3 while True:
4     try:
5         key=i.__next__()
6         print(dic[key])
7     except StopIteration:
8         break

 1 from collections import Iterable,Iterator
 2 
 3 ‘abc‘.__iter__() # 字符串类型
 4 ().__iter__() # 元组类型
 5 [].__iter__() # 列表类型
 6 {‘a‘:1}.__iter__() # 字典类型
 7 {1,2}.__iter__() # 集合类型
 8 
 9 f=open(‘a.txt‘,‘w‘) # 文件类型
10 f.__iter__()

1 print(isinstance(‘abc‘,Iterable)) #True
2 print(isinstance([],Iterable)) # True
3 print(isinstance((),Iterable)) # True
4 print(isinstance({‘a‘:1},Iterable)) # True
5 print(isinstance({1,2},Iterable)) # True
6 print(isinstance(f,Iterable)) # True

1 print(isinstance(‘abc‘,Iterator)) # False
2 print(isinstance([],Iterator)) # False
3 print(isinstance((),Iterator)) # False
4 print(isinstance({‘a‘:1},Iterator)) # False
5 print(isinstance({1,2},Iterator)) # False
6 print(isinstance(f,Iterator)) # True

1 f1=f.__iter__()
2 print(f)
3 print(f1)
4 print(f is f1) # 对于本身就是迭代器的对象来说，执行__iter__方法，得到的结果仍然是它本身

 1 dic={‘name‘:‘egon‘,‘age‘:18,‘height‘:‘180‘}
 2 print(dic.items())
 3 for k,v in dic.items():
 4     print(k,v)
 5 i=iter(dic)
 6 while True:
 7     try:
 8         k=next(i)
 9         print(k)
10     except StopIteration:
11         break
12 上边为for循环的基本工作原理
13 
14 只要是for循环语句就先会将dic变成一个迭代器，然后通过next方法迭代内部元素
15 for k in dic: #i=iter(dic)  k=next(i)
16     print(k)
17     print(dic[k])
18 for循环不同于while循环，for循环本身就是迭代循环，迭代结束之后自动捕捉异常结束

 1 使用return的执行效果
 2 def foo(): # return只能执行一次，函数就会终止，2,3,4不会显示出来
 3     return 1
 4     return 2
 5     return 3
 6     return 4
 7 res1=foo()
 8 print(res1)
 9 res2=foo()
10 print(res2)
11 
12 使用yield的执行效果
13 def foo():
14     print(‘first‘)
15     yield 1
16     print(‘second‘)
17     yield 2
18     print(‘third‘)
19     yield 3
20     print(‘fourth‘)
21     yield 4
22     print(‘fifth‘)
23 
24 g=foo() # g其实就是个迭代器，yield将函数变成了迭代器
25 for i in g:
26     print(i)
27 print(g)
28 print(next(g)) #触发迭代器g的执行，进而触发函数的执行
29 print(next(g)) # 迭代器停靠在yield 2
30 print(next(g)) # 迭代器停靠在yield 3
31 print(next(g)) # 迭代器停靠在yield 4
32 print(next(g))

 1 def counter(n):
 2     print(‘start...‘)
 3     i=0
 4     while i < n:
 5         yield i
 6         i+=1
 7     print(‘end...‘)
 8 g=counter(5)
 9 print(g)
10 print(next(g))
11 print(next(g))
12 print(next(g))
13 print(next(g))
14 print(next(g))
15 print(next(g)) # 报出异常

 1 yield实例化使用：模拟管道符功能的实现
 2 tail -f a.txt | grep ‘python‘
 3 
 4 import time
 5 def tail(filepath):
 6     with open(filepath,encoding=‘utf-8‘) as f:
 7         f.seek(0,2) # 直接跳到文件末尾读取文件
 8         while True:
 9             line=f.readline().strip()
10             if line:
11                 yield line
12             else:
13                 time.sleep(0.2)
14 
15 def grep(pattern,lines):
16     for line in lines: #触发tail函数中的生成器的执行
17         if pattern in line:
18             yield line
19 
20 g=grep(‘python‘,tail(‘a.txt‘))
21 print(g)
22 for i in g: #触发grep函数中的生成器的执行
23     print(i)

  1 print(abs(-1))
  2 print(all([1,2,3])) # 如果每个元素的布尔值都为True，则all的返回值为True
  3 print(all([0,2,3])) # False
  4 print(all(‘‘)) # 如果all中的迭代对象为空，也为True
  5 
  6 print(any([0,None,‘‘,1])) # 只要有一个为True，则返回值为True
  7 print(any([0,None,‘‘])) # 如果都为False的情况下返回False
  8 print(any([])) # 如果any中可迭代对象为空，则返回False
  9 
 10 print(bin(3)) # 将十进制数字转化为二进制
 11 print(hex(17)) # 将十进制数字转化为十六进制
 12 print(oct(9)) # 将十进制数字转化为八进制
 13 
 14 0 None 空 ---> bool值为False，其余都为True
 15 
 16 callable()
 17 def func():
 18     pass
 19 print(callable(func)) # 判断是不是可调用对象
 20 
 21 print(chr(68)) # 将括号中数字按照ASCII码表转化为相应的表中字符
 22 print(ord(‘D‘)) # 将括号中字符按照ASCII码表转化为相应的表中数字
 23 
 24 res=complex(1+2j) # 复数形式，分为实部和虚部
 25 print(res.real)
 26 print(res.imag)
 27 
 28 工厂函数（批量产生特定类型的实例）
 29 dict
 30 int
 31 str
 32 set
 33 list
 34 l=[] ---> #l=list([])
 35 list([1,2,3])
 36 list([‘a‘])
 37 list([‘b‘])
 38 
 39 l=[]
 40 print(dir(l)) # 查看一个对象下面的属性
 41 print(help(l)) # 查看一个对象的帮助信息
 42 
 43 print(divmod(1000,30)) # 得掉商和余数，通常用于分页显示
 44 
 45 x=range(10) # 不是迭代器，但是一个可迭代对象
 46 enumerate([1,2,3]).__next__() # 是迭代器
 47 
 48 cmd=‘print("你瞅啥")‘
 49 eval(cmd) # 将字符串中的命令提取出来执行
 50 dic="{‘a‘:1,‘b‘:2}"
 51 d=eval(dic)
 52 print(type(d),d[‘a‘])
 53 
 54 with open(‘user.db‘,‘w‘,encoding=‘utf-8‘) as f:
 55     user_dic={‘name‘:‘egon‘,‘password‘:‘123‘}
 56     f.write(str(user_dic))
 57 
 58 with open(‘user.db‘,‘r‘,encoding=‘utf-8‘) as f:
 59     dic=f.read()
 60     print(dic,type(dic))
 61     dic=eval(dic)
 62     print(dic[‘name‘])
 63 
 64 s={1,2} #s=set({1,2}) # 定义可变集合
 65 s.add(3)
 66 print(s)
 67 s=frozenset({1,2}) # 定义不可变集合
 68 
 69 
 70 哈希：
 71 1. 只要校验的内容一致，那hash得到结果永远一样
 72 2. 不可逆
 73 3. 只要采用的哈希算法一样，那无论被校验的内容有多长，hash的到的结果长度都一样
 74 print(hash(‘asdfasdfsadf‘))
 75 print(hash(‘asdfasdfsadf‘))
 76 
 77 x=1
 78 y=x
 79 print(id(x),id(y))
 80 print(x is y) # 判断的是身份
 81 a=1
 82 b=1
 83 print(a == b) # 判断的是值
 84 
 85 print(max([1,2,3,4]))
 86 print(pow(10,2,3))
 87 
 88 l=[‘a‘,4,2,3]
 89 for i in reversed(l): # 反转列表
 90     print(i)
 91 print(list(reversed(l)))
 92 
 93 i=reversed(l)
 94 for x in i:
 95     print(x)
 96 print(list(i)) # 列表为空，为什么
 97 
 98 print(round(3.141542653589127134,4)) # 四舍五入取小数点后几位
 99 
100 l=[‘a‘,‘b‘,‘c‘,‘d‘,‘e‘]
101 print(l[1:4:2])
102 s=slice(1,4,2) # 切片用，并且可以重复利用
103 print(l[s])
104 
105 vars() # 如果没有参数相当于locals()
106 
107 s=‘hello‘
108 l=[1,2,3,4,5]
109 z=zip(s,l) # 拉链函数
110 print(z)
111 for i in z:
112     print(i)
113 
114 import time
115 m=__import__(‘time‘) # 以字符串的形式导入模块
116 m.sleep(3000)