What is the pythonic way to calculate dot product?

Question

I have two lists, one is named as A, another is named as B. Each element in A is a triple, and each element in B is just an number. I would like to calculate the result defi

Answer 1

Python 3.5 has an explicit operator @ for the dot product, so you can write

a = A @ B

instead of

a = numpy.dot(A,B)

Answer 2

import numpy
result = numpy.dot( numpy.array(A)[:,0], B)

http://docs.scipy.org/doc/numpy/reference/

If you want to do it without numpy, try

sum( [a[i][0]*b[i] for i in range(len(b))] )

Answer 3

from operator import mul

sum(map(mul, A, B))

Answer 4

This might be repeated solution, however:

>>> u = [(1, 2, 3), (4, 5, 6)]
>>> v = [3, 7]

In plain Python:

>>> sum([x*y for (x, *x2), y in zip(u,v)])
31

Or using numpy (as described in user57368's answer) :

import numpy as np
>>> np.dot(np.array(u)[:,0], v)
31

Answer 5

All above answers are correct, but in my opinion the most pythonic way to calculate dot product is:

>>> a=[1,2,3]
>>> b=[4,5,6]
>>> sum(map(lambda pair:pair[0]*pair[1],zip(a,b)))
32

Answer 6

Using the operator and the itertools modules:

from operator import mul
from itertools import imap

sum(imap(mul, A, B))