Personalization metric calculation optimization

[ibuda]

Hi @statisticianinstilettos,

kudos for a great tool!
I would like to propose an optimization for calculating Personalization Metric here:

#get indicies for upper right triangle w/o diagonal
upper_right = np.triu_indices(similarity.shape[0], k=1)

#calculate average similarity
personalization = np.mean(similarity[upper_right])
return 1-personalization

There is no need to get the upper triangle indices, as the cosine similarity is a symmetric distance.
I will follow up with a pull request for this.

[statisticianinstilettos]

great update! Thanks