iteration - 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 like the following:

for x, y in "abcdef":
    print "%s%s
" % (x, y)
ab
cd
ef

Of course, this doesn't work because it is expecting a single element from the list which itself contains 2 elements.

What is a nice, short, clean, pythonic way to process the next n elements of a list in a batch, or sub-strings of length n from a larger string (two similar problems)?

Answer 1

A generator function would be neat:

def batch_gen(data, batch_size):
    for i in range(0, len(data), batch_size):
            yield data[i:i+batch_size]

Example use:

a = "abcdef"
for i in batch_gen(a, 2): print i

prints:

ab
cd
ef