adding two lists together

Question

I am stuck on a problem involving adding two lists together. For example, if list1 was [1,2,3,4] and list2 was [2,4] I would have to return [3,5,3,4]. Or if list1=[0] and list2=[1] I would return [1]

def addsum(list1,list2):
    new_list = []
    list1[0]+list2[0] = new_list[0]

and so on. This was my first approach but I'm getting a lot of errors. I'm new to lists so I can't use index or lambda functions. I am only allowed to use len(). Would appreciate the help.

I do not understand your first example; shouldn't the result be `[1+2,2+4,3,4]` or `[3,6,3,4]`? — Scott Hunter, Nov 16 '16 at 17:08
First learn what it means to set a variable in Python, i.e. that value goes from right to left. — Rok Povsic, Nov 16 '16 at 17:10
Possible duplicate of [Add SUM of values of two LISTS into new LIST](http://stackoverflow.com/questions/14050824/add-sum-of-values-of-two-lists-into-new-list) — AChampion, Nov 16 '16 at 17:12

score 0 · Answer 1 · edited May 23 '17 at 10:32

You may want to check out 2 python concepts: list comprehension (http://www.secnetix.de/olli/Python/list_comprehensions.hawk) and condensed form of if-else (https://stackoverflow.com/a/2802748/1045285).

l1 = [1, 2, 4, 5]
l2 = [2, 4]
min_len = min(len(l1), len(l2))

rem = l1[min_len:] if len(l1) > len(l2) else l2[min_len:]
res = [e1 + e2 for e1, e2 in zip(l1[:min_len], l2[:min_len])] + rem

adding two lists together

1 Answers1