# How to zip two differently sized lists?

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### Question :

How to zip two differently sized lists?

I want to zip two list with different length

for example

``````A = [1,2,3,4,5,6,7,8,9]
B = ["A","B","C"]
``````

and I expect this

``````[(1, 'A'), (2, 'B'), (3, 'C'), (4, 'A'), (5, 'B'), (6, 'C'), (7, 'A'), (8, 'B'), (9, 'C')]
``````

But the build-in `zip` won’t repeat to pair with the list with larger size .
Does there exist any build-in way can achieve this?
thanks

here is my code

``````idx = 0
zip_list = []
for value in larger:
zip_list.append((value,smaller[idx]))
idx += 1
if idx == len(smaller):
idx = 0
``````

You can use `itertools.cycle`:

Make an iterator returning elements from the iterable and saving a copy of each. When the iterable is exhausted, return elements from the saved copy. Repeats indefinitely.

Example:

``````A = [1,2,3,4,5,6,7,8,9]
B = ["A","B","C"]

from itertools import cycle
zip_list = zip(A, cycle(B)) if len(A) > len(B) else zip(cycle(A), B)
``````

Try this.

``````A = [1,2,3,4,5,6,7,8,9]
B = ["A","B","C"]
Z = []
for i, a in enumerate(A):
Z.append((a, B[i % len(B)]))
``````

Just make sure that the larger list is in `A`.

You can use `itertools.cycle`:

``````from itertools import cycle

my_list = [1, 2, 3, 5, 5, 9]
another_list = ['Yes', 'No']

cyc = cycle(another_list)

print([[i, next(cyc)] for i in my_list])
# [[1, 'Yes'], [2, 'No'], [3, 'Yes'], [5, 'No'], [5, 'Yes'], [9, 'No']]
``````

Do you know that the second list is shorter?

``````import itertools
list(zip(my_list, itertools.cycle(another_list)))
``````

This will actually give you a list of tuples rather than a list of lists. I hope that’s okay.

Solution for an arbitrary number of iterables, and you don’t know which one is longest (also allowing a default for any empty iterables):

``````from itertools import cycle, zip_longest

def zip_cycle(*iterables, empty_default=None):
cycles = [cycle(i) for i in iterables]
for _ in zip_longest(*iterables):
yield tuple(next(i, empty_default) for i in cycles)

for i in zip_cycle(range(2), range(5), ['a', 'b', 'c'], []):
print(i)
``````

Outputs:

``````(0, 0, 'a', None)
(1, 1, 'b', None)
(0, 2, 'c', None)
(1, 3, 'a', None)
(0, 4, 'b', None)
``````

You can use the modulo `%` operator in a loop that counts up

``````my_list=[1, 2, 3, 5, 5, 9]
another_list=['Yes','No']

new_list = []
for cur in range(len(my_list)):
new_list.append([my_list[cur], another_list[cur % 2]])
# [[1, 'Yes'], [2, 'No'], [3, 'Yes'], [5, 'No'], [5, 'Yes'], [9, 'No']]
``````

`2` can be replaced with `len(another_list)`

A very simple approach is to multiply the short list so it’s longer:

``````my_list = [1, 2, 3, 5, 5, 9]
another_list = ['Yes', 'No']

zip(my_list, another_list*3))
#[(1, 'Yes'), (2, 'No'), (3, 'Yes'), (5, 'No'), (5, 'Yes'), (9, 'No')]
``````

Note here that the multiplier doesn’t need to be carefully calculated since `zip` only goes out to the length of the shortest list (and the point of the multiplier is to make sure the shortest list is `my_list`). That is, the result would be the same if `100` were used instead of `3`.

symmetric, no conditionals one liner

``````[*zip(A*(len(B)//len(A) + 1), B*(len(A)//len(B) + 1))]
``````

which strictly answers ‘How to zip two differently sized lists?’

needs a patch for equal sized lists to be general:

``````[*(zip(A, B) if len(A) == len(B)
else zip(A*(len(B)//len(A) + 1),
B*(len(A)//len(B) + 1)))]
``````