Python Iteration Through Lists with Stepped Progression -

given following lists:

letters = ('a', 'b', 'c', 'd', 'e', 'f', 'g') numbers = ('1', '2', '3', '4') 

how can produce iterated list produces following:

output = [('a', '1'), ('b', '2'), ('c', '3'), ('d', '4'),            ('e', '1'), ('f', '2'), ('g', '3'), ('a', '4'),           ('b', '1'), ('c', '2'), ('d', '3'), ('e', '4'),           ('f', '1'), ('g', '2')...] 

i feel should able produce desired output using

output = (list(zip(letters, itertools.cycle(numbers)) 

but produces following:

output = [('a', '1'), ('b', '2'), ('c', '3'), ('d', '4'),           ('e', '1'), ('f', '2'), ('g', '3')] 

any appreciated.

if looking infinite generator, can use cycle zip both lists, in form of zip(itertools.cycle(x), itertools.cycle(y)). supply required generator:

>>> x in zip(itertools.cycle(letters), itertools.cycle(numbers)): ...     print(x) ... ('a', '1') ('b', '2') ('c', '3') ('d', '4') ('e', '1') ('f', '2') ('g', '3') ('a', '4') ('b', '1') ('c', '2') ('d', '3') ...