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

I just meant using lists that contained values within them. – Michael Minkoff Feb 04 '16 at 17:59 — Michael Minkoff, Feb 04 '16 at 17:59
I will update the question – Michael Minkoff Feb 04 '16 at 17:59 — Michael Minkoff, Feb 04 '16 at 17:59

timgeb · Accepted Answer · 2021-05-25T09:04:38.500

23

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.

edited May 25 '21 at 09:04

answered Feb 04 '16 at 18:01

timgeb

76,762
20
123
145

score 1 · Answer 2 · edited Dec 17 '21 at 00:31

1

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

edited Dec 17 '21 at 00:31

answered Dec 17 '21 at 00:30

Plotslut

11
1

score 0 · Answer 3 · edited Mar 10 '22 at 14:50

0

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

edited Mar 10 '22 at 14:50

Ersel Er

731
6
22

answered Mar 10 '22 at 12:08

Ivan Milojevic

9
1

1

The `@` operator is implemented *by* NumPy; it's not part of native Python. – Neil C. Obremski May 19 '22 at 13:17

Dot Product in Python without NumPy

3 Answers3

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