Iterate over a python sequence in multiples of n?

Question

How do I process the elements of a sequence in batches, idiomatically?

For example, with the sequence \"abcdef\" and a batch size of 2, I would like to do something

Answer 1

Here is a solution, which yields a series of iterators, each of which iterates over n items.

def groupiter(thing, n):
    def countiter(nextthing, thingiter, n):
        yield nextthing
        for _ in range(n - 1):
            try:
                nextitem = next(thingiter)
            except StopIteration:
                return
            yield nextitem
    thingiter = iter(thing)
    while True:
        try:
            nextthing = next(thingiter)
        except StopIteration:
            return
        yield countiter(nextthing, thingiter, n)

I use it as follows:

table = list(range(250))
for group in groupiter(table, 16):
    print(' '.join('0x{:02X},'.format(x) for x in group))

Note that it can handle the length of the object not being a multiple of n.