Iterate through adjacent pairs in a generator

Question

I want to access overlapping pairs of adjacent values in a generator.

If it was a list, I could use

a = [5, 7, 11, 4, 5]
for v, w in zip(a[:-1], a[1:]):
    print [v, w]

Which is from this question.

But when I try to do the same with a generator, I get the error

TypeError: 'generator' object is not subscriptable

Is there a way to do this for generators?

You cannot apply slicing or indexing to generators. You must coerce them to lists first. — DYZ, Dec 05 '16 at 18:32
Is there another way to get overlapping pairs in a generator, without any slicing or indexing? — Vermillion, Dec 05 '16 at 18:41
Why didn't you use the top answer from the question you linked? That is essentially what I ended up writing. — SethMMorton, Dec 05 '16 at 19:05
I didn't realize the top answer worked for generators. I tried it, it solves my problem — Vermillion, Dec 05 '16 at 19:29

Robᵩ · Accepted Answer · 2016-12-05T18:55:25.480

5

I would create a generator function to do this:

def adjacent_pairs(it):
    it = iter(it)
    a, b = next(it), next(it)
    while True:
        yield a, b
        a, b = b, next(it)

Example usage:

def gen():
    yield 5
    yield 7
    yield 11
    yield 4
    yield 5
for v, w in adjacent_pairs(gen()):
    print [v, w]

edited Dec 05 '16 at 18:55

answered Dec 05 '16 at 18:43

Robᵩ

1 Answers1