生成器表达式：
#列表推导式
# y = [1,2,3,4,5,6,7,8]
# x = [1,4,9,16,25,36,49,64]
# x = []
# for i in y:
# x.append(i*i)
# print(x)
# x = [i*i for i in y]
# print(x) #range(100)
# x2 = [i/2 for i in range(100)]
# print(x2) #生成器表达式 # x = [i*i for i in y]
# print(x)
# g = (i*i for i in y)
# print(g)
# print(list(g))
# for i in g:
# print(i) #
# l = ['鸡蛋%s'%i for i in range(10)]
# print(l)
# laomuji = ('鸡蛋%s'%i for i in range(10))
# for egg in laomuji:
# print(egg)
生成器函数：
# def cloth():
# for i in range(100):
# yield '衣服%s'%i
#
# g = cloth()
# for i in g:
# print(i) # for i in range(100):
# print(g.__next__())
#
# for i in range(50):
# print(g.__next__()) #监听文件末尾追加的例子
# def tail():
# f = open('文件','r',encoding='utf-8')
# f.seek(0,2)
# while True:
# line = f.readline()
# if line:
# yield line
# import time
# time.sleep(0.1)
# g = tail()
# for i in g:
# print(i.strip()) # send
def func():
print('*'*10)
a = yield 5
print('a : ',a)
yield 10
# g = func()
# num = g.__next__()
# # print(num)
# num2 = g.send('alex')
# num2 = g.send('aaaa')
# print(num2) #从哪一个yield开始接着执行，就把一个值传给了那个yield
#send不能用在第一个触发生成器
#生成器函数中有多少个yield就必须有多少个next+send def averager():
total = 0.0
count = 0
average = None
while True:
term = yield average
total += term
count += 1
average = total/count
#
# g_avg = averager()
# g_avg.__next__()
# print(g_avg.send(10))
# print(g_avg.send(30))
# print(g_avg.send(20))
# print(g_avg.send(100))
# print(g_avg.send(200))
def init(func): #生成器的预激装饰器
def inner(*args,**kwargs):
g = func(*args,**kwargs) #func = averager
g.__next__()
return g
return inner @init
def averager():
total = 0.0
count = 0
average = None
term = yield average
total += term
count += 1
average = total/count
yield average # g_avg = averager()
# print(g_avg.send(10))
# print(g_avg.send(30)) #生成器函数 讲完了
#next
#进阶 send #网络编程 ： ftp
def func():
a = 'AB'
b = 'CD'
yield from a
# for i in a:yield i
yield from b
# for i in b:yield i 'A','B','C','D'
#返回了4次
g = func()
# for i in g:
# print(i) #生成器函数：生成一个生成器的函数
#生成器的本质参数迭代器
#生成器函数的特点：
# 带有yield关键字
# 且调用之后，函数内的代码不执行 #触发执行的方式：
#next
#send (选会) ：send(None) == __next__(),send在next的基础上传一个值到生成器函数内部
#send操作不能用在生成器使用的第一次
#for循环 def cloth():
for i in range(100):
yield '衣服%s'%i g1 = cloth()
g2 = cloth()
print(g.__next__())
print(g.__next__())
# for c in cloth():
# print(c)
# print(g.__next__())
# for i in range(10):
# print(g.__next__())
# for i in range(100):
# print(g.__next__())
# for c in g:
# print(c)
# if c.endswith('80'):
# break
# print(g.__next__())
# print('*'*20)
# for c in g:
# print(c) # g.__next__() #== next(g)
# g.__iter__() #== iter(g)
#内置函数
推导式拓展：
# new_l = []
# for i in range(30):
# if i%3 == 0:
# new_l.append(i)
# print(new_l)
#
# print(list(range(0,30,3)))
# print([i for i in range(30) if i%3 == 0])
# [i*i for i in range(30) if i%3 == 0]
# def square(x):
# return x*x
# [square(i) for i in range(30) if i%3 == 0] # names = [['Tom', 'Billy', 'Jefferson', 'Andrew', 'Wesley', 'Steven', 'Joe'],
# ['Alice', 'Jill', 'Ana', 'Wendy', 'Jennifer', 'Sherry', 'Eva']]
# ret = (name for name_lst in names for name in name_lst if name.count('e') >= 2)
# print(ret)
# 不利于代码可读，但是代码简洁 # mcase = {'a': 10, 'b': 34}
# mcase_frequency = {mcase[k]:k for k in mcase}
# print(mcase_frequency) # mcase = {'a': 10, 'b': 34, 'A': 7, 'Z': 3}
# mcase_frequency = {k.lower(): mcase.get(k.lower(), 0) + mcase.get(k.upper(), 0) for k in mcase}
# print(mcase_frequency) squared = {x**2 for x in [1, -1, 2]} #{1,4}
print(squared)
# Output: set([1, 4]) #考试
#2:00 --> 敲敲代码
#明天 ：
# 装饰器剩余的两个例子
# 今天的考试内容明天要讲
#明天的默写：
#[i/2 for i in range(100)]
#[i*i for i in range(30) if i % 3 is 0]
# 修改成生成器表达式，且要求讲使用方法默写出来
