How to write contents of help to a file from within R?

Question

I'd like to be able to write the contents of a help file in R to a file from within R. The following works from the command-line:

• R --slave -e 'library(MASS); help(survey)' > survey.txt
  • This command writes the help file for the survey data file
  • --slave hides both the initial prompt and commands entered from the resulting output
  • -e '...' sends the command to R
  • > survey.txt writes the output of R to the file survey.txt

However, this does not seem to work:

library(MASS)
sink("survey.txt")
help(survey)
sink()

• How can I save the contents of a help file to a file from within R?

Answer 1

Looks like the two functions you would need are tools:::Rd2txt and utils:::.getHelpFile. This prints the help file to the console, but you may need to fiddle with the arguments to get it to write to a file in the way you want.

For example:

hs <- help(survey)
tools:::Rd2txt(utils:::.getHelpFile(as.character(hs)))

Since these functions aren't currently exported, I would not recommend you rely on them for any production code. It would be better to use them as a guide to create your own stable implementation.