Linking to other packages in documentation in roxygen2 in R
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.
There are two ways to achieve this, using:
1. .Rd syntax
From "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.
2. markdown syntax
From roxygen2 vignette
| roxygen2 comment | description | generated Rd code |
|---|---|---|
[func()] |
func() in this package |
\code{\link[=func]{func()}} |
[pkg::func()] |
func() in the pkg |
\code{\link[pkg:func]{pkg::func()}} |
[thing] |
topic in this package | \link{thing} |
[pkg::thing] |
topic in the pkg |
\link[pkg:thing]{pkg::thing} |
[`thing`] |
topic in this package | \code{\link{thing}} |
[`pkg::thing`] |
topic in the pkg |
\code{\link[pkg:thing]{pkg::thing}} |
Remember to put Roxygen: list(markdown = TRUE) in the DESCRIPTION
Markdown shortcodes available from roxygen2>=6.0.0
You have to type \link[pkg]{function} e.g. \link[stringi]{stri_c}
In addition to the answer by potockan:
Some packages document several functions in a single help page. For example, the trim function from Bioconductor package GenomicRanges is documented in intra-range-methods (which is also the name of a help page from other packages such as IRanges).
To link to the right page with roxygen2 you can use:
\link[GenomicRanges:intra-range-methods]{trim}
or
\code{\link[GenomicRanges:intra-range-methods]{trim}}
to format the text correctly.
The help page will only show trim but will link to the right help page.