Iterate of a list chunk by chunk

listchunk.py

class ListChunk:
    def __init__(self, items, chunksize):
        self.items = items
        self.chunksize = chunksize
        self.ii = 0
    def __iter__(self):
        return self
    def next(self):
        if self.ii >= len(self.items):
            raise StopIteration
        tmp = self.items[self.ii:self.ii + self.chunksize]
        self.ii = self.ii + self.chunksize
        return tmp

items = ListChunk([1,2,3,4,5,5,6,7,8], 2)
for slice in items:
    print slice

Just playing around with custom iterators, etc. It seems like a lot of code to just loop over a list of items by chunking them up. Is there a shorter way to do this?

Here's my take:

class IterChunk(object):
    def __init__(self, items, chunksize):
        self.items = items
        self.chunksize = chunksize
        self._i = 0

    def __iter__(self):
        return self

    def next(self):
        slice = self.items[self._i:(self._i + self.chunksize)]
        self._i += self.chunksize

        if slice:
            return slice

        raise StopIteration

I wouldn't be surprised if there was something in itertools that does this though.

Really the easiest thing to do is just write a generator:

def chunk(l, chunksize):
    for i in range(0, len(l), chunksize):
        yield l[i:i+chunksize]

>>> items = chunk([1,2,3,4,5,5,6,7,8], 2)
>>> for item in items:
...    print item

[1, 2]
[3, 4]
[5, 5]
[6, 7]
[8]

Nice, the generator solution is way better!