The difference between a python-iterator and a generator

Here are a few points of knowledge: iterators, generators, Yieid

Let's look at the difference between iterators and generators with an example.

#L是个list, you can iterate for a loop, l take it out and store it in memory, and then loop it out many times.
>>> l=[x*x for x in range (3)]>>> for I in L:print (i) 014>>> for n in L:print (n) 014

#把 [] becomes a generator, except that it can only be recycled once, because it is not in memory. It is generating data in real time. >>> Mygenerator = (x*x for x in range (3)) >>> for I in Mygenerator:print (i) 014

In fact, I feel the most bad points have the following:

1, the list function call directly results. And the generator is an object

>>> L = [1,2,3,4,5,6]>>> def xh (): For I in L:print (i) >>> g=xh () 123456

>>> l1=[6,7,8,9,10]>>> def generator (): Yield (L1) for I in L1:print (i) >>> g=generator () > >> Next (g) [6, 7, 8, 9, 10]

Here's a yield comparison, let's feel it.

>>> l1=[6,7,8,9,10]>>> def generator (): Yield (L1) #打印L1的意思 for i in L1:print (i) >>> g= Generator () #这里是一个生成器对象 >>> Next (g) #用next打印出来 [6, 7, 8, 9, ten] #生成器第2个例子 >>> def gen2 (): For I in L1:yield (i ) #打印i的值print (i) >>> g=gen2 () >>> print (g) <generator object Gen2 at 0x0000000002eafd00>>> > For x in G:print (x) 667788991010

2, actually think is also quite simple, yield is just a logo, print the results at once

Classic case: Yang Hui Triangle

#将杨辉三角的每一行看成一个list, write a generator (generator) and continuously output the next line listdef Triangel (n):    l=[1]                                                                 #定义一个list [1] while    True:        Yield L                                                           #打印出该list        l=[l[x]+l[x+1] for x in range (len (L)-1)]        #计算下一行中间的值 (except 1 on both sides)        L.insert (0,1)                                                 # Insert 1        l.append (1) at the beginning                                                 #在结尾添加1        if Len (L) >10:                                                 #仅输出10行            break# generates a generator object, Then output each line with a for loop iteration A=angel (Ten) for I in A:    print (i)
#结果 [1][1, 1][1, 2, 1][1, 3, 3, 1][1, 4, 6, 4, 1][1, 5, 10, 10, 5, 1][1, 6, 15, 20, 15, 6, 1][1, 7, 21, 35, 35, 21, 7, 1][1 , 8, 28, 56, 70, 56, 28, 8, 1][1, 9, 36, 84, 126, 126, 84, 36, 9, 1]

The difference between a python-iterator and a generator