Combining Iterables with FillValue

This function is used to combine multiple iterable objects into an iterator. If the iterable objects have different lengths, fillvalue is used to fill the shorter iterable objects.

Technology Stack : itertools

Code Type : Iterator function

Code Difficulty : Intermediate

                
                    
def zip_longest(*iterables, fillvalue=None):
    "Make an iterator that aggregates elements from each of the iterables.
    The iterables must have the same length or be finite. Shorter iterables
    supply fillvalue.

    >>> list(zip_longest([1, 2, 3], 'xyz', fillvalue=-1))
    [1, 2, 3]
    [4, 5, 6]
    [7, 8, 9]
    [10, 11, -1]
    >>> list(zip_longest([1, 2, 3, 4], 'xy', fillvalue=-1))
    [1, 2, 3, 4]
    [5, 6, -1, -1]
    >>> list(zip_longest([1, 2, 3, 4], ['x', 'y', 'z'], fillvalue='-'))
    [1, 2, 3, 4]
    [5, 6, 7, '-']
    >>> list(zip_longest([1, 2, 3, 4], 'xy', fillvalue=()))
    [1, 2, 3, 4]
    [5, 6, 7, ()]
    >>> list(zip_longest([1, 2, 3, 4, 5], ['x', 'y', 'z'], fillvalue=0))
    [1, 2, 3, 4, 5]
    [6, 7, 8, 9, 10]
    [11, 12, 13, 14, 15]
    """
    from itertools import zip_longest as _zip_longest
    return _zip_longest(*iterables, fillvalue=fillvalue)