def gen():print("爽歪歪")yield "娃哈哈" # 可以让我们的函数分段运行print("酸酸乳")yield "AD钙奶"print("黄焖鸡米饭")ret = gen() # 不会执行你的函数, 获取到生成器对象
# 迭代器不能等价代换
print(ret) # <generator object gen at 0x00000195518CFE60> generator 生成器
print(ret.__next__()) # 必须执行__next__()才可以触发生成器的运行 娃哈哈
print(ret.__next__()) # 必须执行__next__()才可以触发生成器的运行 AD钙奶
print(ret.__next__()) # StopIteration 迭代器, 就找yield, 执行不到才会报错

def gen():lst = []for i in range(1, 10000):lst.append("衣服%s" % i)if i % 50 == 0: #  1 2 3 4 5 6 7 8 9 .. 49  50yield lstlst = [] # 每次生成一个新列表g = gen() # 获取到生成器print(g.__next__())
print(g.__next__())
print(g.__next__())
print(g.__next__())
print(g.__next__())

def func():print("水饺")a = yield "大馅水饺"print("a=", a)print("烧饼")b = yield "武大郎烧饼"print("b=",b)print("老婆饼")c = yield "只要老婆不要饼"print("c=", c)

gen = func() # 生成器
print("返回值是:", gen.__next__())
print("返回值是:",gen.send("混沌面")) #  和__next__()一样也是向下找yield. 给上一个yield传值
print("返回值是:",gen.send("胡辣汤")) #  和__next__()一样也是向下找yield. 给上一个yield传值
print("返回值是:",gen.send("马拉"))   # 和__next__()一样也是向下找yield. 给上一个yield传值

def  func():print("哈哈")yield  "呵呵"print("吼吼")return  "嘻嘻" # don't do this!
gen = func()gen.__next__()gen.__next__()

lst = ["中岛美雪", "夏川美里", "原由子", "汪峰", "田震","那英","周杰伦"]
new_lst = [ el for el in lst if len(el) == 2]  #此处快速创建了一个新列表,并用IF语句做出来筛选
print(new_lst)

[3,6,9]  已知 求转换成[(1,2,3), (4,5,6), (7,8,9)]lst = [3,6,9]
new_lst = [(el-2, el-1, el) for el in lst]

实例一
lst = [11, 22, 33]  #  => {0:11, 1:22, 2:33}
dic = {i:lst[i] for i in  range(len(lst)) }  #字典推导式
print(dic)
实例二
dic = {"张无忌":"赵敏", "杨过":"小龙女", "郭靖":"黄蓉"}
# 把字典中的key和value互换
# dic = {"赵敏":"张无忌", "小龙女":"杨过", "黄蓉":"郭靖"}
法1
dic1 = { v:k for k, v in dic.items()}  # 强化
print(dic1)
法2
dic2 = { dic[k]:k for k in dic} # 强化
print(dic2)

lst = ["衣服%s" % i for i in range(100000000)] # 占内存
print(lst)g = ("衣服%s" % i for i in range(100000000)) # 生成器表达式. 节省内存,要多少多少
print(g.__next__())
print(g.__next__())
print(g.__next__())
print(g.__next__())

g = (i for i in range(10))
print(list(g)) # 把传递进来的数据转化成列表.  里面包含了for循环
list() => for=> __iter__() ==> __next__()
print(list(g)) # 上一次已经拿没了,因为生成器是一次性的,且只能往前取值,所以会打印出空表格
print(g.__next__())
for el in g:print(el)
for el in g: # 已经没有数据了 惰性机制-> 只能往前print(el)

def func(): # 生成器函数print(111)yield 222
g = func()          #  生成器 -> 没有执行过__next__()
g1 = (i for i in g)  # 生成器表达式. 也没有__Next__()
g2 = (i for i in g1) # 生成器表达式. 也没有__Next__()
# 到此为止, 没有人拿过值
print(list(g))  #  111 [222]
print(list(g1)) #  []   #因为前面的g已将拿过值了,g已经空了,先到先得
print(list(g2)) # []

def gen():lst1 = ["⿇花藤", "胡辣汤", "微星牌饼铛", "Mac牌锅铲"]lst2 = ["饼铛还是微星的好", "联想不能煮鸡蛋", "微星就可以", "还可以烙饼"]yield from lst1yield from lst2
g = gen()
for el in g:print(el)   #结果会先将lst1先打印完,然后再打印lst2