Python学习day4

 

一、迭代器&生成器

1. 列表[0, 1, 2, 3, 4, 5, 6, 7, 8, 9],要求你把列表里的每个值加1，有以下几种方法：

(1)a = [1,3,4,6,7,7,8,9,11]

for index,i in enumerate(a):
    a[index] +=1
print(a)

 

(2) [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

>>> a = map(lambda x:x+1, a)

 

(3)a = [i+1 for i in range(10)]

2.斐波那契数列

def fib(max):
    n,a,b = 0,0,1
    while n < max:
        yield b
        a,b, = b,a+b
        n += 1
    return 'done'
f = fib(10)
print(f.__next__())
print("======")
for i in f:
    print(i)

 

二、装饰器

1.

#定义：本质是函数，为其他函数添加附加功能
#原则：1.不能修改被装饰的函数的源代码
    #  2.不能修改被装饰的函数的调用方式
# 知识储备：
# 1.函数即变量
# 2.高阶函数
#         a：吧一个函数名当做实参传给另一个函数(在不修改被装饰函数源代码的情况下为其添加功能)
#         b：换回值中包含函数名(不能修改函数的调用方式)
# 3.嵌套函数
import time
def timmer(func):
    def warpper(*args,**kwargs):
        start_time = time.time()
        func()
        stop_time = time.time()
        print('the func run time is %s' %(stop_time - start_time))
    return warpper()

@timmer
def test1():
    time.sleep(3)
    print("in the test1")
test1()

2.import time
# def bar():
#     time.sleep(2)
#     print('in the bar')
#
# def test1(func):
#     start_time = time.time()
#     func()  #run bar
#     stop_time = time.time()
#     print("the func run time is %s" %(stop_time - start_time))
#
# test1(bar)

def bar():
    time.sleep(2)
    print('in the bar')
def test2(func):
    print(func)
    return func

#print(test2(bar))
bar = test2(bar)
bar()

 

3.#嵌套函数
def foo():
    print('in the foo')
    def bar():
        print('in the bar')

    bar()
foo()

 

4.import time
def timer(func):
    def deco(*args,**kwargs):
        start_time = time.time()
        func(*args,**kwargs)
        stop_time = time.time()
        print("%s" %(stop_time - start_time))
    return deco

@timer #相当于test1 = timer(test1),在需要添加功能的函数上加上
def test1():
    time.sleep(1)
    print('int the test1')
@timer #test2 = timer(test2) = deco test2(name) = deco(name)
def test2(name,age):
    print('in the test2:',name,age)

test1()
test2("alex",22)

 

5. 高级版装饰器

import time
user,passwd = 'alex','abc123'
def auth(func):
    def wrapper(*args,**kwargs):
        username = input("Username:").strip()
        password = input("Password:").strip()
        if user == username and passwd == password:
            print("\033[32;1mUser has passed authentication\033[0m")
            res = func(*args,**kwargs)
            print("---")
            return res
        else:
            exit("\033[32;1mInvalid input\033[0m")
    return wrapper

def index():
    print("welcome to index page")
@auth
def home():
    print("welcome to home page")
    return "from home"
@auth
def bbs():
    print("welcome to bbs page")

index()
print(home())
bbs()

 

6. 生成器并行

import time
def consumer(name):
    print("%s 准备吃包子啦!" %name)
    while True:
       baozi = yield

       print("包子[%s]来了,被[%s]吃了!" %(baozi,name))

def producer(name):
    c = consumer('A')
    c2 = consumer('B')
    c.__next__() #必须next一下
    c2.__next__()
    print("老子开始准备做包子啦!")
    for i in range(10):
        time.sleep(1)
        print("做了1个包子!")
        c.send(i)
        c2.send(i)

producer("alex")

 

三、Json & pickle 数据序列化

1.json序列化1

#import json
import pickle

def sayhi(name):
    print("hello",name)

info = {
    'name':'alex',
    'age':22,
    'func':sayhi
}
f = open("test.txt","wb")
#print(json.dumps(info))
#f.write(json.dumps(info))#序列化用dumps
f.write(pickle.dumps(info))
f.close()

 

2. json反序列化1

#import json
import pickle
def sayhi(name):
    print("hello2",name)

f = open("test.txt","rb")

data = pickle.loads(f.read())#反序列化用loads

print(data["age"])

3. json序列化2

import pickle

def sayhi(name):
    print("hello",name)

info = {
    'name':'alex',
    'age':22,
    'func':sayhi
}
f = open("test.test","wb")
pickle.dump(info,f) #f.write(pickle.dumps(info))
f.close()

 

4. json反序列化2

import pickle
def sayhi(name):
    print("hello2",name)
f = open("test.txt","rb")
data = pickle.load(f)#data = pickle.loads(f.read())#反序列化用loads
print(data["age"])

 

四、内置方法大全

#abs()#取绝对值

#all
# 回归True如果可迭代是真(或者如果迭代是空的)
# print(all([1,-5,3]))

# any(可迭代)
# 回归True如果可迭代是真的。如果可迭代为空，则返回False
# print(any([0,1]))

# bin(x)
# 将整数转换为以“0b”为前缀的二进制字符串

# a = bytes("abcde",encoding="utf-8")
# b = bytearray("abcde",encoding="utf-8")
# print(b[1])
# b[1] = 50
# print(b)

#判断这个函数是否能调用
# def sayhi(): pass
# print(callable(sayhi))

#chr(98)把字符转换成ASKII码
#ord('b)反过来

#(lambda n:print(n))(5) 匿名函数传参
# calc = lambda n:print(n**n) #lambda只能处理三元运算，复杂的处理不了了
# calc(5)

#filter:过滤出你想要的
# fil = filter(lambda n:n>5,range(10))
# for i in fil:
#     print(i)

#map:对每个值都处理
# res = map(lambda n:n*n,range(10))
# for i in res:
#     print(i)

# import functools
# res = functools.reduce(lambda x,y:x+y,range(10))#累加
# print(res)

#frozenset不可变的列表
#a = frozenset([1,2,44])

#打印所有变量，字典方式
#print(globals())

#hex()#变成16进制
#print(hex(255))

#locals()只有local里面有局部变量
# def test():
#     local_var = 333
#     print(locals())
# test()
# print(globals())
# print(globals().get('local_var'))

#oct返回8进制
#pow a的b次方
#print(pow(2,3))

#round保留小数点

#sorted
# a = {6:2,8:0,1:4,-5:6,99:11,4:22}
# print(sorted(a.items(),key = lambda x:x[1])) #列表排序出来,key = lambda x:x[1])是按照value排序
# print(a)

#zip拼接函数
# a = [1,2,3,4]
# b = ['a','b','c','d']
# zz = zip(a,b)
# for i in zz:
#     print(i)