PyTorch for Recommenders 101

Recommenders, generally associated with e-commerce, sift though a huge inventory of available items to find and recommend ones that a user will like. Different from search, recommenders rely on historical data to tease out user preference. How does a recommender accomplish this? In this post we explore building simple recommendation systems in PyTorch using the Movielens 100K data, which has 100,000 ratings (1-5) that 943 users provided on 1682 movies. We first build a traditional recommendation system based on matrix factorization.