Question

Sometimes on an R help page the phrase “not run” appears in comments. Check out this from the help page for “with()”:

Examples
require(stats); require(graphics)
#examples from glm:
**## Not run:** 
library(MASS)
with(anorexia, {
    anorex.1 <- glm(Postwt ~ Prewt + Treat + offset(Prewt),
                    family = gaussian)
    summary(anorex.1)
})
## End(**Not run**)

What does the “not run” mean in the example code?

Answer 1

“not run” encloses code that shouldn’t be executed in the example function (e.g. time-consuming code parts, user-interaction, …).

see e.g. ?example:

As detailed in the manual Writing R Extensions, the author of
the help page can markup parts of the examples for two exception
rules

• ‘dontrun’ encloses code that should not be run.

• ‘dontshow’ encloses code that is invisible on help pages, but will
  be run both by the package checking tools, and the
  ‘example()’ function. This was previously ‘testonly’, and
  that form is still accepted.