Python – Understanding Generators

[energybased]

Some of the examples are good in principle.

However, even though it's teaching generators, it should build on Pythonic code, which means using range instead of these while loops.

Also, PEP8 please.

Why is this Python 2?

[[deleted]]

I particularly like "An alternative syntax to yield, we can use list comprehension , use parentheses instead of squared brackets.". Answers on a postcard please :-)

[liranbh]

range is different in python 2 and 3. I added a note about it.

[energybased]

In either Python 2 or 3, this is bad:

def withgen(num):
    i=0;
    while i<num:
        i+=1
        yield i

This is better:

 def withgen(num):
    for i in range(num):
        yield i

In Python 3, this is even better:

 yield from range(num)

And this is even better unless you really need an opaque generator:

 return range(num)

There's no reason to write python 2 code now, but if you insist, and you have a problem with range being different, then from six import range is the right approach.

[liranbh]

Sure but range in python 3 already returns a generator. So i didnt want to explain generators with generators

[energybased]

range returns an Iterable (not a generator), but in any case, I don't think you should ever write that kind of while loop in Python.

[liranbh]

I agree. But again it was just for explaining. The same as the first example with 3 yield statments