R Data Analysis Projects

Memory-based approach

The memory-based approach to collaborative filtering loads the whole rating matrix into memory to provide recommendations, hence the name memory-based model. User-based filtering is the most prominent memory-based collaborative filtering model. The R snippet explained in the preceding section is the underlying principle by which memory-based methods work. As the user and product base grows, scalability is a big issue with memory-based models.

In the R snippet example, we used the ratings of user.b to fill in the missing ratings for user.a. In the real world, with thousands of users, the user-based filtering algorithm first proceeds as follows.

Let us say we have a set of users {u₁,u₂.....u_n} and a set of products {p ...