Categories / group-by
Grouping by ID and Outcome and Creating a Wide Format Output in R's Tidyverse Package: A Step-by-Step Guide to Achieving a Consecutive Number for Each New Phase of Recovery Per Patient.
Implementing Time Lag in R with dplyr and data.table
Selecting Rows with Maximal Values in a Column Using Pandas GroupBy Operations
Solving Duplicate Data in SQL Case Statements with MAX() Function