Grouping lists within lists in Python 3

Question

I have a list of lists of strings like so:

List1 = [
          [\'John\', \'Doe\'], 
          [\'1\',\'2\',\'3\'], 
          [\'Henry\', \'Doe\'], 
          [         


        

Answer 1

Here it is in 8 lines. I used tuples rather than lists because it's the "correct" thing to do:

def pairUp(iterable):
    """
        [1,2,3,4,5,6] -> [(1,2),(3,4),(5,6)]
    """
    sequence = iter(iterable)
    for a in sequence:
        try:
            b = next(sequence)
        except StopIteration:
            raise Exception('tried to pair-up %s, but has odd number of items' % str(iterable))
        yield (a,b)

---

Demo:

>>> list(pairUp(range(0)))    
[]

>>> list(pairUp(range(1)))
Exception: tried to pair-up [0], but has odd number of items

>>> list(pairUp(range(2)))
[(0, 1)]

>>> list(pairUp(range(3)))
Exception: tried to pair-up [0, 1, 2], but has odd number of items

>>> list(pairUp(range(4)))
[(0, 1), (2, 3)]

>>> list(pairUp(range(5)))
Exception: tried to pair-up [0, 1, 2, 3, 4], but has odd number of items

---

Concise method:

zip(sequence[::2], sequence[1::2])
# does not check for odd number of elements