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What is yield keyword in python and give an example?

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What is yield keyword in python and give an example?
posted Feb 4, 2015 by Gnanendra Reddy

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1 Answer

+1 vote

Yield is a keyword that is used like return, except the function will return a generator, so lets first understand the generator -

Generators are iterators, but you can only iterate over them once. It’s because they do not store all the values in memory, they generate the values on the fly:

>>> mygen = (x*x for x in range(3))
>>> for i in mygen:
...    print(i)

Output 
0
1
4

you can not perform for i in mygen a second time since generators can only be used once.

Now coming back to yield which by definition is a keyword that is used like return, except the function will return a generator, see the following example for more clarity -

>>> def createGenerator():
...    mylist = range(3)
...    for i in mylist:
...        yield i*i
...
>>> mygen = createGenerator() 
>>> print(mygen)

Output
0
1
4
answer Feb 4, 2015 by Salil Agrawal
already return keyword is there in python  i really didnt understand "for i in mygen a second time since generators can only be used once "sir please give me some more explanation
return will return after the first iteration and second&third would not even complete. Is this answers your query.
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