A company is building a recommender system using implicit feedback (clicks) and explicit feedback (ratings). They plan to use Amazon SageMaker to train a model. The data includes user ID, item ID, timestamp, and rating (if any). Which TWO data preparation steps should the team perform? (Choose TWO.)
Matrix factorization algorithms (e.g., in SageMaker's built-in Factorization Machines) require user and item IDs as integers.
Why this answer
Matrix factorization algorithms in Amazon SageMaker (e.g., the built-in Factorization Machines algorithm or the Apache Spark-based collaborative filtering) require user and item identifiers to be converted to contiguous integer indices starting from 0. This is necessary for efficient embedding lookup and to avoid memory blowup from sparse categorical features. SageMaker's implementation expects the input data in recordIO-wrapped protobuf format with integer-encoded user and item columns.
Exam trap
The trap here is that candidates confuse one-hot encoding (which is common in linear models) with the integer indexing required for embedding-based models like matrix factorization, leading them to select Option D instead of Option A.