itertools.zip_longest

itertools.zip_longest(*itr, fillvalue=None)

• The zip_longest function is used to:

  • Cycle through each element of each iterable
  • Maps elements from each of the iterables together
  • If the iterables are uneven length, missing values are filled with fillvalue
• This iterables are based on the *itr parameter
• This filled value is based on the fillvalue parameter
• The fillvalue parameter is optional and defaults to None
• zip_longest returns an iterator of elements zipped to each other

Illustrating the zip_longest Function

>>> from itertools import zip_longest
>>> nums = [1,2,3]
>>> letters = 'yz'
>>> fruit = 'apple'

>>> itr = zip_longest(nums, letters)
>>> for i in itr: print(i)
(1, 'y')
(2, 'z')
(3, None)

>>> itr = zip_longest(letters, fruit, fillvalue='-')
>>> for i in itr: print(i)
('y', 'a')
('z', 'p')
('-', 'p')
('-', 'l')
('-', 'e')

References

• Documentation of the Zip_longest Function from Itertools