How can I add the corresponding elements of several lists of numbers?

Question

I have some lists of numbers:

[1, 2, 3, 4, 5]
[2, 3, 4, 5, 6]
[3, 4, 5, 6, 7]

How can I add these lists\' elements, assuming that all of th

Answer 1

How about:

a = [1,2,3,4,5]
b = [2,3,4,5,6]
c = [3,4,5,6,7]

s = map(sum, zip(a,b,c))

Answer 2

Using numpy:

>>> seq = np.array([
... [1,2,3,4,5],
... [2,3,4,5,6],
... [3,4,5,6,7]])
>>> np.sum(seq,axis=0)
array([ 6,  9, 12, 15, 18])

Answer 3

Try this functional style code:

>>> map(sum, zip(*lists))
[6, 9, 12, 15, 18]

The zip function matches elements with the same index.

>>> zip(*lists)
[(1, 2, 3), (2, 3, 4), (3, 4, 5), (4, 5, 6), (5, 6, 7)]

Then sum is applied to each tuple by using map.

See it working online: ideone

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Note that in Python 3.x, map no longer returns a list. If you need the list, please see the following question:

• Getting a map() to return a list in Python 3.x

(You can just call list).

Answer 4

Assuming:

a = [1,2,3,4,5]
b = [2,3,4,5,6]
c = [3,4,5,6,7]

just do this:

[sum(n) for n in zip(*[a, b, c])]

Answer 5

>>> lis=[[1,2,3,4,5],[2,3,4,5,6],[3,4,5,6,7]]

>>> [sum(x) for x in zip(*lis)]
[6, 9, 12, 15, 18]

Answer 6

This one works for lists with various length too(nested only 1 time).

def sum_list_of_list_of_int(ll):
    l=[]
    for i in ll:  # "i" type is list
        for ii in range(len(i)):  # "ii" type is int
            if len(l)-1>=ii:
                l[ii]+=int(i[ii])
            else:
                l.append(int(i[ii]))
    return l