Zipping Differently Sized Lists Using Built-In Functions

While the built-in zip function is unable to repeat the shorter list when merging two differently sized lists, you can leverage the itertools.cycle function to achieve this outcome.

cycle from the Python package itertools creates an iterator that repeatedly returns elements from an iterable, even after its exhaustion. By combining zip with cycle, it's possible to handle the size discrepancy between the lists and ensure that the longer list is repeated as necessary.

Example:

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

# Use itertools.cycle to repeat the shorter list
from itertools import cycle
zip_list = zip(A, cycle(B)) if len(A) > len(B) else zip(cycle(A), B)

In this example:

• if len(A) > len(B) checks if the first list (A) is longer than the second (B).
• If so, it uses zip to merge A with a cycling iterator of B, effectively repeating B throughout the merged result.
• If B is longer, it flips the order and cycles A instead.

Result:

zip_list will contain the following tuples as a generator object:

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

How it Works:

itertools.cycle creates a copy of the iterable (in this case, B) and repeatedly returns its elements. As zip iterates through A, it pairs each element with the next available element from the cycling iterator.

If A is shorter than B, the process starts over from the beginning of B once its iterator is exhausted. Conversely, if A is longer, the B iterator cycles continuously to fill the remainder of the merged list.