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pythonnumpymatrixcosine-similarity
Nilani Algiriyage
Nilani Algiriyage

Reputation: 35636

Calculate cosine similarity of two matrices

I have defined two matrices like following:

from scipy import linalg, mat, dot
a = mat([-0.711,0.730])
b = mat([-1.099,0.124])

Now, I want to calculate the cosine similarity of these two matrices. What is the wrong with following code. It gives me an error of objects are not aligned

c = dot(a,b)/np.linalg.norm(a)/np.linalg.norm(b)

Upvotes: 5

Views: 21005

Answers (2)

Qy Zuo
Qy Zuo

Reputation: 2732

also: 

import numpy as np
import scipy.spatial.distance as distance
a = np.array([0.1, 0.2])
b = np.array([0.3,0.4])
c = 1 - distance.cosine(a, b)

see: https://docs.scipy.org/doc/scipy/reference/generated/scipy.spatial.distance.cosine.html#scipy.spatial.distance.cosine

Upvotes: 6

lejlot
lejlot

Reputation: 66775

You cannot multiply 1x2 matrix by 1x2 matrix. In order to calculate dot product between their rows the second one has to be transposed.

from scipy import linalg, mat, dot
a = mat([-0.711,0.730])
b = mat([-1.099,0.124])

c = dot(a,b.T)/linalg.norm(a)/linalg.norm(b)

Upvotes: 9

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