Non-interactive debugging

When you can’t explore interactively…

callr::r()

callr::r(f, list(1, 2)) calls f(1, 2) in a fresh session to help diagnose:

• Is the global environment different? Have you loaded different packages? Are objects left from previous sessions causing differences?

• Is the working directory different?

• Is the PATH environment variable different?

• Is the R_LIBS environment variable different?

dump.frames()

dump.frames() is the equivalent to recover() for non-interactive code.

Print debugging

Insert numerous print statements to precisely locate the problem, and see the values of important variables. Print debugging is particularly useful for compiled code.

RMarkdown

• If you’re knitting the file using RStudio, switch to calling rmarkdown::render("path/to/file.Rmd") instead to run the code in the current session.

• For interactive debugging, you’ll need to call sink() in the error handler. For example, to use recover() with RMarkdown, you’d put the following code in your setup block: