Is there a built-in function that works like zip(), but fills the results so that the length of the resulting list is the length of the longest input and fills the list from the left with e.g. None?

There is already an answer using zip_longest from itertools module and the corresponding question is very similar to this. But with zip_longest it seems that you can only fill missing data from the right.

Here might be a use case for that, assuming we have names stored only like this (it's just an example):

header = ["title", "firstname", "lastname"]
person_1 = ["Dr.", "Joe", "Doe"]
person_2 = ["Mary", "Poppins"]
person_3 = ["Smith"]

There is no other permutation like (["Poppins", "Mary"], ["Poppins", "Dr", "Mary"]) and so on.

How can I get results like this using built-in functions?

>>> dict(magic_zip(header, person_1))
{'title': 'Dr.', 'lastname': 'Doe', 'firstname': 'Joe'}
>>> dict(magic_zip(header, person_2))
{'title': None, 'lastname': 'Poppins', 'firstname': 'Mary'}
>>> dict(magic_zip(header, person_3))
{'title': None, 'lastname': 'Smith', 'firstname': None}

Use zip_longest but reverse lists.

Example:

from itertools import zip_longestheader = ["title", "firstname", "lastname"]
person_1 = ["Dr.", "Joe", "Doe"]
person_2 = ["Mary", "Poppins"]
person_3 = ["Smith"]print(dict(zip_longest(reversed(header), reversed(person_2))))
# {'lastname': 'Poppins', 'firstname': 'Mary', 'title': None}

On your use cases:

>>> dict(zip_longest(reversed(header), reversed(person_1))) 
{'title': 'Dr.', 'lastname': 'Doe', 'firstname': 'Joe'}
>>> dict(zip_longest(reversed(header), reversed(person_2)))
{'lastname': 'Poppins', 'firstname': 'Mary', 'title': None} 
>>> dict(zip_longest(reversed(header), reversed(person_3))) 
{'lastname': 'Smith', 'firstname': None, 'title': None}