In my Python 3 script, I am trying to make a combination of three numbers from three different lists based on inputs. If the lists are the same size, there is no issue with zip. However, I want to be able to input a single number for a specific list and the script to repeat that number until the longest list is finished. This can be done with zip_longest. However, with fillvalue it is not possible to have separate fill values for separate lists.
Taking this simple script as an example:
from itertools import zip_longest
list1=[1]
list2=[4, 5, 6, 7, 8, 9]
list3=[2]
for l1, l2, l3 in zip_longest(list1, list2, list3):
print(l1, l2, l3)
This is the actual result:
# 1 4 2
# None 5 None
# None 6 None
# None 7 None
# None 8 None
# None 9 None
And this would be the result that I want:
# 1 4 2
# 1 5 2
# 1 6 2
# 1 7 2
# 1 8 2
# 1 9 2
I already managed to do this specific task by manually creating different for loops and asking if a list is a constant or not, but zip_longest is so close to exactly what I need that I wonder if I am missing something obvious.
You could make use of logical or operator to use the last element of the shorter lists:
from itertools import zip_longest
list1 = [1]
list2 = ["a", "b", "c", "d", "e", "f"]
list3 = [2]
for l1, l2, l3 in zip_longest(list1, list2, list3):
print(l1 or list1[-1], l2, l3 or list3[-1])
Out:
1 a 2
1 b 2
1 c 2
1 d 2
1 e 2
1 f 2