Element-Wise Addition of 2 Lists

Element-wise addition of 2 lists?

Use map with operator.add:

>>> from operator import add
>>> list( map(add, list1, list2) )
[5, 7, 9]

or zip with a list comprehension:

>>> [sum(x) for x in zip(list1, list2)]
[5, 7, 9]

Timing comparisons:

>>> list2 = [4, 5, 6]*10**5
>>> list1 = [1, 2, 3]*10**5
>>> %timeit from operator import add;map(add, list1, list2)
10 loops, best of 3: 44.6 ms per loop
>>> %timeit from itertools import izip; [a + b for a, b in izip(list1, list2)]
10 loops, best of 3: 71 ms per loop
>>> %timeit [a + b for a, b in zip(list1, list2)]
10 loops, best of 3: 112 ms per loop
>>> %timeit from itertools import izip;[sum(x) for x in izip(list1, list2)]
1 loops, best of 3: 139 ms per loop
>>> %timeit [sum(x) for x in zip(list1, list2)]
1 loops, best of 3: 177 ms per loop

Element to Element addition of two lists in python

print [i+ j for i in list1 for j in list2]

I think ... if I understand the question right?

if you have

list1 = [1, 2, 3, 4, 5, 6]
list2 = [1, 2, 3, 4, 5, 6]

then this will result in

[ 2,3,4,5,6,7, 3,4,5,6,7,8, 4,5,6,7,8,9, 5,6,7,8,9,10, 6,7,8,9,10,11, 7,8,9,10,11,12]

which sounds like what you want

or do it the cool numpy way

from itertools import chain
l2 = numpy.array(list2)
print chain(*[l2+i for i in list1])

How to sum the elements of 2 lists in python?

you can use zip/map:

result = list(map(sum,zip(list1,list2)))

Alternative, via list_comprehension:

result = [i+j for i,j in zip(list1,list2)]

OUTPUT:

[11, 13, 15, 17, 19]

sum of N lists element-wise python

Just do this:

[sum(x) for x in zip(*C)]

In the above, C is the list of c_1...c_n. As explained in the link in the comments (thanks, @kevinsa5!):

* is the "splat" operator: It takes a list as input, and expands it into actual positional arguments in the function call.

For additional details, take a look at the documentation, under "unpacking argument lists" and also read about calls (thanks, @abarnert!)

Add SUM of values of two LISTS into new LIST

The zip function is useful here, used with a list comprehension.

[x + y for x, y in zip(first, second)]

If you have a list of lists (instead of just two lists):

lists_of_lists = [[1, 2, 3], [4, 5, 6]]
[sum(x) for x in zip(*lists_of_lists)]
# -> [5, 7, 9]

Element-wise addition of two lists of different lengths?

There's an alternative zip that does not stop at the shortest: itertools.zip_longest(). You can specify a fill value for the shorter lists:

from itertools import zip_longest

result = [sum(n) for n in zip_longest(a, b, fillvalue=0)]

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