day 13 生成器，推导式

1. 生成器和生成器函数

　　生成器的本质就是迭代器

　　生成器的三种创建办法:
　　　　1.通过生成器函数

　　　　2.通过生成器表达式创建生成器

　　　　3.通过数据转换

# def func():
#     print("我是周杰伦")
#     yield "昆凌"  # 函数中包含了yield, 当前这个函数就不再是普通的函数了. 是生成器函数
#     print("我是王力宏")
#     yield "李云迪???"
#     print("我是笛卡尔积")
#     yield "笛卡尔积是谁"
    # print("你好啊") # 最后一个yield之后如果再进行__next__() 会报错
# g = func()
# print(g.__next__())
# print(func().__next__())
#
# g1 = func()
# g2 = func()
# print(g1.__next__())
# print(g1.__next__())
#
# print("==============")
# print(g2.__next__())

生成器函数:

　　函数中包含了yield的就是生成器函数

　　注意:生成器函数被执行. 获取到的是生成器. 而不是函数的执行

生成器表达式:

　　(结果 for 变量 in 可迭代对象 if 筛选)

取值:

　　1. __next__()

　　2. send(值) 给上一个yield位置传一个值, 第一个和最后一个yield不用传值

　　3. 可以for循环

　　4. list(g)

# g = func()  # 通过函数func()来创建一个生成器
# print(g.__next__()) # 周杰伦
# print(g.__next__()) # 王力宏
# print(g.__next__()) # 笛卡尔积
# print(g.__next__())

# return 直接返回结果. 结束函数的调用
# yield 返回结果.可以让函数分段执行
#
# def func():
#     lst = []
#     for i in range(1,100001):
#         lst.append("衣服%s" % i)
#     return lst
#
# def gen():
#     i = 1
#     while i < 100001:
#         yield "衣服%s" % i
#         i = i + 1
# g = gen()
# print(g.__next__())
# print(g.__next__())
# print(g.__next__())
# print(g.__next__())
# print(g.__next__())
# print(g.__next__())

#
# def func():
#     yield 11
#     yield 22
#     yield 33
#     yield 44

# g = func()  # 拿到的是生成器. 生成器的本质是迭代器. 迭代器可以被迭代 生成器可以直接for循环
#
# for i in g:
#     print(i)    # 本质上执行的是__next__()
#
# it = g.__iter__()
# while True:
#     try:
#         print(it.__next__())
#     except StopIteration:
#         break

2. 各种推倒式和生成器表达式

　　1. 列表推倒式 [结果 for 变量 in 可迭代对象 if 筛选]

# 生成列表 里面装1-14的数据
# lst = []
# for i in range(1,15):
#     lst.append("python%s" % i)
# print(lst)

# 列表推倒式; 最终给你的是列表
# 语法 [最终结果(变量) for 变量 in 可迭代对象]

# lst = [i for i in range(1,15)]
# print(lst)

# [最终结果 for 变量 in 可迭代对象 if 条件]
lst = [i for i in range(1,101) if i%2==0]
print(lst)

# 1. 获取1-100内能被3整除的数
# lst = [i for i in range(1,101) if i % 3 == 0]
# 2. 100以内能被3整除的数的平方
# lst = [i*i for i in range(1,101) if i % 3 == 0]
# 3. 寻找名字中带有两个e的⼈的名字
# names = [['Tom', 'Billy', 'Jefferson' , 'Andrew' , 'Wesley' , 'Steven' ,
# 'Joe'],['Alice', 'Jill' , 'Ana', 'Wendy', 'Jennifer', 'Sherry' , 'Eva']]
# lst = [name for first in names for name in first if name.count("e") == 2]
# print(lst)
#
# lst = ["衣服%s" % i for i in range(10000)]

　　2. 字典推倒式 {结果 for 变量 in 可迭代对象 if 筛选} 结果=>key:value

# g = (i for i in range(10))
# print(list(g))

# gen = ("麻花藤我第%s次爱你" % i for i in  range(10))
# for i in  gen:
#     print(i)

# 生成器的惰性机制
# def func():
#     print(111)
#     yield  222
# g = func()
# g1 = (i  for i in  g)
# g2 = (i  for i in  g1)
#
# print(list(g))
# print(list(g1))
# print(list(g2))

# dic = {"a":"b", "c":"d"}
# # 把字典中的key:value互换 .{"b":"a", "d":"c"}
# new_dic = {dic[key]:key for key in dic}
# print(new_dic)

# lst1 = ["alex", "wusir", "taibai", "ritian"]
# lst2 = ['sb', "很色", "很白", "很牛"]
# # {"alex":"sb", "wusir":"很色"}
#
# dic = { lst1[i]:lst2[i] for i in range(len(lst1))}
# print(dic)



# dic = {"a":"b","c":"d"}
# #把字典中的key:value互换.{"b":"a":"d":"c"}
# new_dic = {dic[key]:key for key in dic}
# print(new_dic)
#
# #lst1 = ["alex","wusir","taibai","ritian"]
# #lst2 = ['sb',"很色","很白","很牛"]
# #{"alex":"sb","wusir":"很色"}
# dic = {lst1[1]:lst2[i] for i in range(len(lst1))}
# print(dic)
#
# dic = {"a":"b","c":"d"}


# name = "aleX leNb"
# e1 = name.find("e", 0,5)
# print(e1)
#
# e2 = name.find("e",5)
# print(e2)

# count = 1
# while count <= len(name):
#     if name[count] =='e':
#         print(count)
#     count = count + 1
#
# s = "123a4b5c"
# s = "asdfer"
# for c in s:     #c :chartor
#     print(c)

# content = input("请输入内容")
# lst = content.split("+")
# s1 = lst[0]
# s2 = lst[1]
# a1 = int(s1)
# a2 = int(s2)
# print(a1+a2)
#
# lst = ["皇阿玛", "皇额娘", "容嬷嬷", "紫薇"]
# it = lst.__iter__()
# while True:
#     try:
#         name = it.__next__()
#         print(name)
#     except StopIteration:
#         break
#
#
# dic = {"a":"b", "c":"d"}
# new_dic = {dic[key]:key for key in dic}  #字典的key和value对调
# print(new_dic)
#
#
# lst1 = ["alex","wusir","taibai","ritian"]
# lst2 = ['sb',"很色","很白","很牛"]
# dic = {lst1[i]:lst2[i] for i in range(len(lst1))}
# print(dic)
# #列表1和列表二合并，1作为key，2作为value



# def func():
#     print("111")
#     return 222
# ret = func()
# print(ret)


# def func():
#     print("111")
#     yield 222
# ret = func()
# print(ret)



g = (i for i in range(10))
print(list(g))

　　3. 集合推倒式 {结果 for 变量 in 可迭代对象 if 筛选} 结果=>key

lst = ["马化腾", "马化腾", "王建忠", "张建忠", "张建忠", "张雪峰", "张雪峰"]

s = {i for i in lst}    # 集合推倒式
print(s)

def add(a, b):
    return a + b
def test():
    for i in range(4):
        yield i
g = test()

def func():
    name = "alex"
    def inner():
        print(name)
    inner()
    print(inner.__closure__)
func()

　　

def add(a, b):
    return a + b


def gen():
    for r_i in range(4):
         yield r_i


g = gen()

for n in [2, 10]:
    g = (add(n, i) for i in g)
print(list(g))