Search code examples
pythonnumpymatrixcosine-similarity

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)
Solution

  • 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)