Sum lists of variable lengths element-wise
python
Solution
Use `izip_longest` to remap rows/columns (like `zip` but to the longest element rather than shortest), filling shorter items 0
from itertools import izip_longest
total = [sum(x) for x in izip_longest(*allLists, fillvalue=0)]
Outputs:
[12, 15, 18, 10]
Also for your edification, the intermediate output of the zip_longest is:
[(1, 4, 7), (2, 5, 8), (3, 6, 9), (0, 0, 10)]
Problem
If I have a list of lists, and each nested list contains numbers, how can I add all of these lists element-wise into a single array? i.e. ``` listOne = [1, 2, 3] listTwo = [4, 5, 6] listThree = [7, 8, 9, 10] allLists = [listOne, listTwo, listThree] total = add(allLists) print total ``` output should be `[12, 15, 18, 10]`