Extract the Title from an Rd Help File

Searches all .Rd files in a package's man/ directory for a given topic (matched against \\alias entries) and returns its \\title string.

Usage

rdTitle(topic, man = "man")

Arguments

topic

a single character string giving the topic (function name or alias) to look up.

man

a single character string giving the path to the directory containing .Rd files. Defaults to "man", i.e. the man/ subdirectory of the current working directory.

Value

a single character string with the title, trimmed of leading and trailing whitespace. Stops with an error if topic is not found.

See also

tools::parse_Rd()

Other pkg.funinfo: funArgs(), funCalls(), funKeywords(), funList(), rdLabels()

Examples

# a minimal man/ directory to search in
man <- file.path(tempdir(), "man")
dir.create(man, showWarnings = FALSE)

writeLines(c("\\\\name{foo}", "\\\\alias{foo}", "\\\\alias{bar}",
             "\\\\title{A Minimal Help Page}",
             "\\\\description{Nothing to see here.}"),
           file.path(man, "foo.Rd"))

rdTitle("foo", man = man)
#> Warning: /tmp/RtmpR25AXN/man/foo.Rd:1: unexpected '{'
#> [1] NA
rdTitle("bar", man = man)          # aliases are matched as well
#> Warning: /tmp/RtmpR25AXN/man/foo.Rd:1: unexpected '{'
#> [1] NA
rdTitle("nothing", man = man)      # NA
#> Warning: /tmp/RtmpR25AXN/man/foo.Rd:1: unexpected '{'
#> [1] NA

unlink(man, recursive = TRUE)