item_similarity_recommender not consistent with docs formula

apple / turicreate

Turi Create simplifies the development of custom machine learning models.

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item_similarity_recommender not consistent with docs formula #3425

Open mats-claassen opened 3 years ago

mats-claassen commented 3 years ago

Hi. The documentation for the item_similarity_recommender states that it computes predictions as:

for cosine and jaccard similarities.

However, the library seems to compute the predictions as:

where #Iu is the number of ratings user u has given. This would be the same as replacing SIM(i, j) in the denominator of the original formula with 1.

Could someone confirm this? Is it a documentation error?