Dot Product in Python without NumPy

Question

Is there a way that you can preform a dot product of two lists that contain values without using NumPy or the Operation module in Python? So that the code is as simple as it could get?

For example:

V_1=[1,2,3]
V_2=[4,5,6]

Dot(V_1,V_2)

Answer: 32

Answer 1

Without numpy, you can write yourself a function for the dot product which uses zip and sum.

>>> def dot(v1, v2):
...     return sum(x*y for x, y in zip(v1, v2))
... 
>>> dot([1, 2, 3], [4, 5, 6])
32

As of Python 3.10, you can use zip(v1, v2, strict=True) to ensure that v1 and v2 have the same length.

Answer 2

def dot_product(x, y):
    dp = 0
    for i in range(len(x)):
        dp += (x[i]*y[i])
    return dp

sample1 = [1,2,3,4,5]
sample2 = [2,1,1,1,1]

dot_product(sample1, sample2) #16

Answer 3

We can simply use @ operator from python. For example:

import numpy as np
x = np.array([25, 2, 5])
y = np.array([0, 1, 2])

print(x@y)
12