How exactly does a generator comprehension work?

Question

What does generator comprehension do? How does it work? I couldn\'t find a tutorial about it.

Answer 1

Generator comprehension is an easy way of creating generators with a certain structure. Lets say you want a generator that outputs one by one all the even numbers in your_list. If you create it by using the function style it would be like this:

def allEvens( L ):
    for number in L:
        if number % 2 is 0:
            yield number

evens = allEvens( yourList )

You could achieve the same result with this generator comprehension expression:

evens = ( number for number in your_list if number % 2 == 0 )

In both cases, when you call next(evens) you get the next even number in your_list.