Element-wise addition of 2 lists?
elementwise-operations, list, python
Solution
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
Problem
I have now: ``` list1 = [1, 2, 3] list2 = [4, 5, 6] ``` I wish to have: ``` [1, 2, 3] + + + [4, 5, 6] || || || [5, 7, 9] ``` Simply an element-wise addition of two lists. I can surely iterate the two lists, but I don't want do that. What is the most Pythonic way of doing so?