A Guided Tour of rtables - Advanced

Contributed by Johnson & Johnson Innovative Medicine

Gabriel Becker

Dan Hofstaedter

2025-12-27

Scope and Audience

We saw in the previous intermediate portion of this tour that a well engineered library of analysis, group summary, and split functions can combine to support a massive array of different individual tables. Whether we are tasked with maintaining and extending those libraries or simply with creating custom tables outside of that supported space, we sometimes need to write new custom functions. By the end of this portion of the tour we will have the tools necessary to do that. While gaining those tools, we will also become more familiar with the structure of TableTree objects (how rtables models tables) and how to interact with them once they are created.

Upon learning the material in this portion of the training, users will be able to fully exploit the flexibility and power of the rtables layout and table engines to create virtually any desired table in cases when their existing function library falls short.

Chapters

• Custom Analysis and Group Summary Functions Core concepts for creating custom analysis and group summary functions
  • Structure-Conditional Behavior In afuns With .spl_context Creating afun/cfun behavior conditional on location within the table structure using .spl_context and other optional arguments.
  • Calling Existing afuns Within Custom afuns Details about what in_rows returns and how we can use that to wrap or combine existing afuns or cfuns
  • Useful Behavioral Building Blocks For Complex Custom afuns Examples of prototypical behaviors which can be reused and combined when writing custom afuns
• Custom Split Functions Core concepts for creating custom split functions
  • Using make_split_fun Effectively make_split_fun and recognizing when to specify pre, core, and post behavior customizations
  • Using And Combining Provided Behavior Building Blocks The split function behavior building blocks provided by rtables and how to use and combine them
  • Writing Reusable Behavior Building Blocks Writing new custom split function behaviors so that they are reusable
  • Some Complex Worked Examples Combining these topics to create complex custom split functions
• Understanding and Interacting With TableTree Objects Understanding how rtables models tables and how to interact with them after creation
  • Table Structure and Pathing Table structure and describing locations within a table via pathing (existing vignette)
  • Accessing Values Within A Table Retrieving values from a table
  • Writing Custom Scoring Functions For Sorting Writing custom scoring functions for use with sort_at_path
  • Writing Custom Pruning Functions Writing custom pruning functions for use with prune_table