Linking to other packages in documentation in roxygen2 in R

You have to type \link[pkg]{function} e.g. \link[stringi]{stri_c}

Roxygen2 now also supports documentation written in markdown.

The markdown syntax is for the link is [foo::bar()] which is translated to \code{\link[foo:bar]{foo::bar()}} in the generated .Rd file. (See Roxygen2 vignette.)

Note that you may need to specifically turn on Markdown support by writing Roxygen: list(markdown = TRUE) in your DESCRIPTION file, or by putting an #' @md comment if you want to enable markdown only for a specific man page. This is also explained at the very top of the linked vignette. (Thanks to @Tjebo for the comment)

Note that there are two colons in the markdown version whereas there is only one colon in the Rd version.

Using .Rd syntax ("R packages" book):

• \code{\link{function}} - function in this package.
• \code{\link[MASS]{abbey}} - function in another package.
• \link[=dest]{name} - link to dest, but show name.
• \code{\link[MASS:abbey]{name}} - link to function in another package, but show name.
• \linkS4class{abc} - link to an S4 class.

Using markdown (roxygen2 vignette)

Remember to put Roxygen: list(markdown = TRUE) in the DESCRIPTION
Markdown shortcodes available from roxygen2>=6.0.0