Multiple Tuple to Two-Pair Tuple in Python?

Question

What is the nicest way of splitting this:

tuple = ('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h')

into this:

tuples = [('a', 'b'), ('c', 'd'), ('e', 'f'), ('g', 'h')]

Assuming that the input always has an even number of values.

Answer 1

[(tuple[a], tuple[a+1]) for a in range(0,len(tuple),2)]

Answer 2

zip() is your friend:

t = ('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h')
zip(t[::2], t[1::2])

Answer 3

Here's a general recipe for any-size chunk, if it might not always be 2:

def chunk(seq, n):
    return [seq[i:i+n] for i in range(0, len(seq), n)]

chunks= chunk(tuples, 2)

Or, if you enjoy iterators:

def iterchunk(iterable, n):
    it= iter(iterable)
    while True:
        chunk= []
        try:
            for i in range(n):
                chunk.append(it.next())
        except StopIteration:
            break
        finally:
            if len(chunk)!=0:
                yield tuple(chunk)

Answer 4

Or, using itertools (see the recipe for grouper):

from itertools import izip
def group2(iterable):
   args = [iter(iterable)] * 2
   return izip(*args)

tuples = [ab for ab in group2(tuple)]