Python 学习笔记-10

Python学习笔记-10:

  1. 装饰器的应用
  2. 列表生成式
  3. 生成器
  4. 迭代器
  5. 模块:time,random

1. 装饰器的应用-登陆练习

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login_status = False    # 定义登陆状态
def type(auth_type): # 装饰器传参函数
def login(fucn): # 装饰器函数
def inner(): # 附加功能
global login_status # 将登陆状态变量变为全局变量
if login_status == False:
if auth_type == 'jingdong':
username = input('username:')
password = input('password:')
with open('jingdong.txt','r') as f:
lines = f.readlines()
for i in lines:
i = eval(i)
if username in i and password == i[username]:
print('welcome %s' % (username))
login_status = True
fucn()
else:
print('wrong username or password')
elif auth_type == 'weixin':
username = input('username:')
password = input('password:')
with open('weixin.txt', 'r') as f:
lines = f.readlines()
for i in lines:
i = eval(i)
if username in i and password == i[username]:
print('welcome %s' % (username))
login_status = True
fucn()
else:
print('wrong username or password')
else:
pass
return inner
return login

@type('jingdong') # 连接装饰器
def home(): # 功能函数
print('welcome to home page')

@type('weixin')
def finance():
print('welcome to finance page')

@type('jingdong')
def book():
print('welcome to book page')


if __name__ == '__main__':

while True:
print('welcome to JD:')
print('choice 1 to home')
print('choice 2 to finance')
print('choice 3 to book')
print('choice 0 to back')
choice = input('Where are you going:')
if choice == '1':
home()
elif choice == '2':
finance()
elif choice == '3':
book()
elif choice == '0':
break

2. 列表生成式

代码示例:

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a = [x for x in range(10)]
print(a) # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

a = [x*2 for x in range(10)]
print(a) # [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

def f(n):
return n**3

a = [f(x) for x in range(10)]
print(a) # [0, 1, 8, 27, 64, 125, 216, 343, 512, 729]

3. 生成器

代码示例:

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# 第一种方法
s = (x for x in range(100)) # 生成器
# for的作用:消除内存占用,判断遍历完成
for i in s:
print(i)
# 第二种方法
def foo():
i = range(22)
yield i

for i in foo():
print(i)
# send方法给yield赋值
def bar():
print('ok1')
count = yield 1 # 接收'ee'
print(count)
print('ok2')
yield 2

b = bar()
b.send(None) # 相当于next(b)
b.send('ee') # 将'ee'赋值给第一个yield

4. 迭代器

  • 生成器都是迭代器
    什么是迭代器?
  1. 有iter方法
  2. 有next方法

5. 模块

1. time模块

函数/方法:
time() – return current time in seconds since the Epoch as a float
clock() – return CPU time since process start as a float
sleep() – delay for a number of seconds given as a float
gmtime() – convert seconds since Epoch to UTC tuple
localtime() – convert seconds since Epoch to local time tuple
asctime() – convert time tuple to string
ctime() – convert time in seconds to string
mktime() – convert local time tuple to seconds since Epoch
strftime() – convert time tuple to string according to format specification
strptime() – parse string to time tuple according to format specification
tzset() – change the local timezone

代码示例:

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print(time.strftime('%Y-%m-%d  %H:%M:%S'))    #2017-09-20  13:44:01

print(time.strptime('2017-09-20 12:53:21','%Y-%m-%d %H:%M:%S'))
# time.struct_time(tm_year=2017, tm_mon=9, tm_mday=20, tm_hour=12, tm_min=53, tm_sec=21, tm_wday=2, tm_yday=263, tm_isdst=-1)

2. random模块

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print(random.randint(1,8))        # 从1-8中随机取值
print(random.choice('hello')) # 从‘hello’中随机取一个字母
# 实现验证码
def v_code():
code = ''
for i in range(5):
add = random.choice([random.randrange(10),chr(random.randrange(65,91))])
code += str(add)
print(code)

v_code()