Recommender System

There are two very important types of relationships between products: substitute and complementary. Substitute products are those that are interchangeable while complementary products are those that might be purchased in addition. For example, when a user is looking at a T-shirt, substitute products are other different types of T-shirts and complementary products can be shorts, hoodies or jackets. Swing is designed for substitute relationships and Surprise is designed for complementary relationships....

UserCF UserCF uses ratings of the target item from top N similar users to predict the rating from the current user. There are mainly two steps: Steps 1. Calculate similarities between users. There are three common ways of calculating user similarities: a. Jaccard Similarity: $$J_{u,v} = \frac{|N(u) \cap N(v)|}{|N(u) \cup N(v)|}$$ $N(u)$ denotes the interacted item set of user $u$. b. Cosine Similarity: $$cos(u,v) = \frac{u\cdot v}{|u|\cdot|v|}$$ $u$ and $v$ denote the rating vectors of two users respectively....