Concise vector adding in Python? [duplicate]

Answer 1

You could create a function that gets the size of the array, loops through it and creating a return array which it returns.

Answer 2

An improvement (less memory consumption) of the comprehension list

import itertools a = [x+y for x,y in itertools.izip(a,b)]

Actually if you are not sure that a will be consume then I would even go with generator expression:

(x+y for x,y in itertools.izip(a,b))

Answer 3

If you need efficient vector arithmetic, try Numpy.

>>> import numpy
>>> a=numpy.array([0,1,2])
>>> b=numpy.array([3,4,5])
>>> a+b
array([3, 5, 7])
>>> 

Or (thanks, Andrew Jaffe),

>>> a += b
>>> a
array([3, 5, 7])
>>> 

Answer 4

For the general case of having a list of lists you could do something like this:

In [2]: import numpy as np

In [3]: a = np.array([[1, 1, 1], [2, 2, 2], [3, 3, 3],[4, 5, 6]])

In [4]: [sum(a[:,i]) for i in xrange(len(a[0]))]
Out[4]: [10, 11, 12]

Answer 5

a = map(lambda x, y: x + y, a, b)

Answer 6

[a[x] + b[x] for x in range(0,len(a))]