In [1]: [x for x in range(10)]
Out[1]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
In [3]: [x*2 for x in range(10)]             ##可以对列表做操作,生成新的列表
Out[3]: [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

先定义一个函数
In [5]: def f(n):...:     return n**3for循环调用
In [6]: [f(x) for x in range(10)]
Out[6]: [0, 1, 8, 27, 64, 125, 216, 343, 512, 729]
In [7]: a=[f(x) for x in range(10)]
In [8]: type(a)
Out[8]: list

In [9]: t=('393',8)
In [10]: a,b=t
In [11]: a
Out[11]: '393'
In [12]: b
Out[12]: 8

In [13]: s=(f(x) for x in range(10))            #修改封闭方式,把中括号修改成小括号
In [14]: print(s)
<generator object <genexpr> at 0x7f7ddef4b0a0>  ##生成器对象In [15]: [f(x) for x in range(100000000000000000000)]
Killed

In [3]: s=(x for x in range(10))
In [4]: s.__next__()        ##在python2上调用没有下划线,但是在python3是内部特殊方法的调用,不建议这样使用
Out[4]: 0
In [5]: s.__next__()
Out[5]: 1
In [6]: next(s)            ##python3上建议使用的内置方法,超出range(10)的范围会报错,因为迭代结束
Out[6]: 2
In [7]: next(s)
Out[7]: 3

In [8]: for i in s:...:     print(i)...:
4
5
6
7
8
9

In [4]: def f():...:     return 1...: f()...:
Out[4]: 1

In [12]: def f():...:     print('ok')...:     yield 1          ##类型于return的功能,把1返回,如果下面再有代码不会执行,除非再加yield...:     print('ok')...:     yield 2...:                     ##在yield 2后面有一个默认的return none,代表函数结束
In [13]: a=f()               ##f()是一个生成器对象,赋值给a,这个结束后不会执行f,不会执行fIn [14]: print(a)
<generator object f at 0x7f013e847a40>  ##是一个生成器对象,只要有yield就是生成器对象In [15]: next(a)
ok
Out[15]: 1  #return 1In [16]: next(a)
ok
Out[16]: 2  #return 2

In [17]: for i in f():...:     print(i)...:
ok
1
ok
2
#for内部实际运行过程
In [18]: for i in f():...:     while True:...:         i=next(f())

In [48]: def boo():...:     print('ok1')...:     yield 1...:     print('ok2')...:     yield 2
In [49]: b=boo()
In [50]: next(b)
ok1
Out[50]: 1
In [51]: b.send('bbb')   ##没报错
ok2
Out[51]: 2

In [52]: def boo():...:     print('ok1')...:     count=yield 1...:     print(count)...:     yield 2
In [53]: b=boo()
In [54]: b.send(None)     ##相当于next(b)
ok1
Out[54]: 1                ##已经返回1
In [55]: b.send('bbb')
bbb
Out[55]: 2

In [5]: import timeIn [6]: def consumer(name):                       ##吃苹果的人...:     print("%s Prepare apple!" %name)      ##传入参数A是人名,准备苹果,接着是B...:     while True:...:         apple = yield                     ##yield状态停住,下次有参数传入,apple可以接收...:         print("apple[%s]is coming,[%s]eat!"%(apple,name))...:         In [7]: def producer(name):                       ##生产苹果的人,一产一吃达到这种并发的效果...:     c = consumer('A')             ##创建两个变量,执行consumer函数分别传入参数A,B...:     c2 = consumer('B')            ##这两行生成一个生成器对象...:     c.__next__()                  ##通过next执行,返回,A准备吃苹果...:     c2.__next__()                 ##通过next执行,返回,B准备吃苹果...:     print("I am ready to eat!")...:     for i in range(2):...:         time.sleep(1)...:         print("prepare two apples!")  ##就可以准备,模拟停止了1秒钟,准备两个苹果...:         c.send(i)  ##发送i给c生成器对象,c带i进入到consumer函数apple=yield中,i就给apple这个变量,for i in range(2),从0开始,apple=0,就打印apple[0]is coming,[A]eat!,然后while循环继续又回到yield,c.send(i)就执行完成,再到c2.send(i)执行...:         c2.send(i)In [8]: producer("reid")
A Prepare apple!
B Prepare apple!
I am ready to eat!
prepare two apples!
apple[0]is coming,[A]eat!
apple[0]is coming,[B]eat!
prepare two apples!
apple[1]is coming,[A]eat!
apple[1]is coming,[B]eat!

# 0 1 1 2 3 5 8 13 21
In [18]: def fibo(max):...:     n,before,after=0,0,1  ##n是第几位,before前一位数,after是后一位数...:     while n < max:        ...:         print(after)      ##从1开始打印...:         before,after=after,before+after
#第2位1的值已经打印出来,要做相应的计算,一开始before是0,after是1,移位后before是1,after是before+after=0+1...:         n = n + 1         ##让n+1进行下一次打印,第二次打印after,从1还是变成1
In [32]: fibo(6)
1
1
2
3
5
8In [33]: def fibo(max):...:     n, before, after=0, 0, 1...:     while n < max:...:         print(before)...:         before,after=after,before+after...:         n = n + 1...:         In [34]: fibo(6)   ##打印before从0开始
0
1
1
2
3
5

before=1
after=2
before,after=after,before+after
描述:先从右边开始运行before,after=(after=2),(before+after=1+2=3),再给左边赋值
使用yield来返回,使用next来调用斐波那契数列
In [35]: def fibo(max):...:     n,before,after=0,1,1...:     while n<max:...:         yield before  #yield有断层,第一次执行完后,把这个状态保存了,下次再从这里开始...:         before,after=after,before+after...:
In [37]: fibo(6)
Out[37]: <generator object fibo at 0x7f013d4a7990>   #生成器对象,传入的6并不在内存地址,在调用时才会取,而且有限制
In [38]: a=fibo(5)
In [39]: next(a)
Out[39]: 1
In [40]: next(a)
Out[40]: 1
In [41]: next(a)
Out[41]: 2