How to toggle roxygen comments in Rstudio?

Question

Roxygen comments involve prefixing lines with #'. When writing and testing examples for functions, it's nice to be able to toggle the comments on and off. I could copy and paste the code back and forward to vim and remove or add those comments, but that's not very elegant.

Is there any easy way to toggle roxygen comments in Rstudio?
Alternatively, is there another way to efficiently run example R code that is commented out by roxygen comment characters?

Update: Thinking laterally, I suppose using @example examples/foo.r is an alternative way of avoiding having to use Roxygen comments for the actual example code (i.e., by sourcing the example from a file, i.e., examples/foo.r).

I've seen people comment code by `if(TRUE/FALSE) {}`. You can toggle that with one letters. — Roman Luštrik, Oct 05 '13 at 09:24

ctbrown · Answer 1 · 2016-10-26T12:23:49.290

With respect to your proposed alternative:

Alternatively, is there another way to efficiently run example R code that is commented out by roxygen comment characters?

If you press CTRL+[Enter] within a Roxygen2 @examples block, Rstudio will send the selected code (line or highlighted section) to the R console. To use just declare the @examples code block on a line preceding your roxygen commented code.

#' @examples
#'   ... your original roxygen commented code ...

You can put an @examples block anywhere in your code. This becomes a drag if you are developing a package and you are using the block for its intended purpose.

If you are looking for a way to toggle code, I would use the approach proposed by @Roman in in the comments to your question.

score 2 · Answer 2 · answered Oct 05 '13 at 10:42

You can write your own function that extract example code from your R file. This is analogous to purl in knit package or Stangle. Here an example of what you can do. The function is not efficient but I write it just to show the idea. It should be a good start point. It assumes also that you already source your R file or at least that the documented function already exist in the R session.

purl.examples <- function(fileName){
  ll <- readLines(fileName)
  ex.lines <- grep('@examples',ll)   ## get the example's lines
  ## for each example loop till
  ## there is no comment (inefficient)
  examples  <- lapply(ex.lines , function(x){
    i <- x+1
    code <- list()
    while(grepl("#'",ll[i])){
      l <- c(code,gsub("#'","",ll[i],fixed=TRUE))
      i <- i+1      
    }
    code
  })
}

Then you can call it like this for example:

lapply(purl.examples('code.R'), 
       function(ex) eval(parse(text=ex))) ## safer to use evaluate package here

How to toggle roxygen comments in Rstudio?

2 Answers2