[Python-ideas] itertools.chunks(iterable, size, fill=None)

[MRAB]

On 01/09/2012 07:27, anatoly techtonik wrote:
> I've run into the necessity of implementing chunks() again. Here is
> the code I've made from scratch.
>
> def chunks(seq, size):
>    '''Cut sequence into chunks of given size. If `seq` length is
>       not divisible by `size` without reminder, last chunk will
>       have length less than size.
>
>       >>> list( chunks([1,2,3,4,5,6,7], 3) )
>       [[1, 2, 3], [4, 5, 6], [7]]
>    '''
>    endlen = len(seq)//size
>    for i in range(endlen):
>      yield [seq[i*size+n] for n in range(size)]
>    if len(seq) % size:
>      yield seq[endlen*size:]
>
Here's a lazy version:

def chunks(seq, size):
     '''Cut sequence into chunks of given size. If `seq` length is
        not divisible by `size` without reminder, last chunk will
        have length less than size.

        >>> list( chunks([1,2,3,4,5,6,7], 3) )
        [[1, 2, 3], [4, 5, 6], [7]]
     '''
     if size < 1:
         raise ValueError("chunk size less than 1")

     it = iter(seq)

     try:
         while True:
             chunk = []

             for _ in range(size):
                 chunk.append(next(it))

             yield chunk
     except StopIteration:
         if chunk:
             yield chunk