# How to zip two differently sized lists, repeating the shorter list?

## Question:

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 built-in `zip`

won’t repeat to pair with the list with larger size.

Does there exist any built-in way can achieve this?

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
```

## Answers:

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`

.

There is probably a better way, but you could make a function that repeats your list to whatever length you want.

```
def repeatlist(l,i):
'''give a list and a total length'''
while len(l) < i:
l += l
while len(l) > i:
l.pop()
```

Then do

```
repeatlist(B,len(A))
zip_list = zip(A,B)
```

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)))]
```

And nowadays with list comprehentions

```
[(i, B[i % 3 - 1]) for i in A]
```

Or if the elements of `A`

are not sequential and not worrying about list lengths

```
[(j, B[i % len(B)]) for i, j in enumerate(A)] if len(A) >= len(B) else
[(A[i % len(A)], j) for i, j in enumerate(B)]
```

For a version that works with any finite number of potentially infinite iterables in any order:

```
from itertools import cycle, tee, zip_longest
def cyclical_zip(*iterables):
iterables_1, iterables_2 = zip(*map(tee, iterables)) # Allow proper iteration of iterators
for _, x in zip(
zip_longest(*iterables_1), # Limit by the length of the longest iterable
zip(*map(cycle, iterables_2))): # the cycling
yield x
assert list(cyclical_zip([1, 2, 3], 'abcd', 'xy')) == [(1, 'a', 'x'), (2, 'b', 'y'), (3, 'c', 'x'), (1, 'd', 'y')] # An example and test case
```

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)
```

```
d1=['one','two','three']
d2=[1,2,3,4,5]
```

### Zip

```
zip(d1,d2)
<zip object at 0x05E494B8>
```

### list of zip

```
list(zip(d1,d2))
```

### dictionary of list of zip

```
{'one': 1, 'two': 2, 'three': 3}
```

Note: Python 3.7+

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']]
```

Try like this:

```
my_list=[ 1, 2, 3, 5, 5, 9]
another_list=['Yes','No']
if type(len(my_list)/2) == float:
ml=int(len(my_list)/2)+1
else:
ml=int(len(my_list)/2)
print([[x,y] for x,y in zip(my_list,another_list*ml)])
```

Native way:

- Try to calculate and round the half of the length of first list, if it is float then add 1 too
- Iterate using
`zip()`

before that multiply second YesNo list with the calculated number before

Let’s use `np.tile`

and `zip`

:

```
my_list = [1, 2, 3, 5, 5, 9]
another_list = ['Yes', 'No']
list(zip(my_list,np.tile(another_list, len(my_list)//len(another_list) + 1)) )
```

Output:

```
[(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.

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`

.

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)`

I like Henry Yik’s answer and it’s a bit faster to execute, but here is an answer without using itertools.

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

This question is trying to solve a problem the wrong way.

What you are trying here is to get all possible permutations of the elements of two given lists. This can be easily achieved using `itertools.product`

```
>>> from itertools import product
>>> list(product(range(2), range(5)))
[(0, 0), (0, 1), (0, 2), (0, 3), (0, 4), (1, 0), (1, 1), (1, 2), (1, 3), (1, 4)]
>>> list(product(range(2), range(2)))
[(0, 0), (0, 1), (1, 0), (1, 1)]
>>> list(product(range(2), range(2), range(3)))
[(0, 0, 0), (0, 0, 1), (0, 0, 2), (0, 1, 0), (0, 1, 1), (0, 1, 2), (1, 0, 0), (1, 0, 1), (1, 0, 2), (1, 1, 0), (1, 1, 1), (1, 1, 2)]
```