| help {base} | R Documentation |
These functions provide access to documentation.
Documentation on a topic with name name (typically, an R
object or a data set) can be printed with either help(name) or
?name.
help(topic, offline = FALSE, package = .packages(),
lib.loc = .lib.loc, verbose = getOption("verbose"),
try.all.packages = getOption("help.try.all.packages"),
htmlhelp = getOption("htmlhelp"),
pager = getOption("pager"))
?topic
topic |
a name or character string on which documentation is sought (but not a variable containing a character string!). |
offline |
a logical indicating whether documentation should be displayed on-line to the screen (the default) or hardcopy of it should be produced. |
package |
a name or character vector giving the packages to look into for documentation. By default, all packages in the search path are used. |
lib.loc |
a character vector of directory names of R libraries. Defaults to all libraries currently known. If the default is used, the loaded packages are searched before the libraries. |
verbose |
logical; if TRUE, the file name is reported. |
try.all.packages |
logical; see Notes. |
htmlhelp |
logical (or NULL). If TRUE (which is the
default after help.start has been called), the HTML
version of the help will be shown in a browser. |
pager |
the pager to be used for file.show. |
In the case of unary and binary operators and control-flow special forms, the name may need to be quoted.
If offline is TRUE, hardcopy of the documentation is
produced by running the LaTeX version of the help page through
latex (note that LaTeX 2e is needed) and dvips.
Depending on your dvips configuration, hardcopy will be sent to
the printer or saved in a file. If the programs are in non-standard
locations and hence were not found at compile time, you can either set
the options latexcmd and dvipscmd, or the environment
variables R_LATEXCMD and R_DVIPSCMD appropriately.
The appearance of the output can be customized through a file
`Rhelp.cfg' somewhere in your LaTeX search path.
Unless lib.loc is specified explicitly, the loaded packages are
searched before those in the specified libraries. This ensures that
if a library is loaded from a library not in .lib.loc then the
help from the loaded library is used. If lib.loc is specified
explicitly, the loaded packages are not searched.
If this search fails and argument try.all.packages is
TRUE and neither packages nor lib.loc is
specified, then all the packages in lib.loc are searched
for help on topic and a list of (any) packages where help
may be found is printed (but no help is shown).
N.B. searching all packages can be slow.
The help files can be many small files. On some file systems it is desirable to save space, and the text files in the `help' directory of an installed package can be zipped up as a zip archive `Rhelp.zip'. Ensure the files `AnIndex' and `00Titles' remain un-zipped. Similarly, all the files in the `latex' directory can be zipped to `Rhelp.zip'.
help.search() for finding help pages on a ``vague'' topic.
help.start() which opens the HTML version of the R
help pages;
library() for listing available packages and the
user-level objects they contain;
data() for listing available data sets;
methods().
See prompt() to get a prototype for writing help
pages of private packages.
help()
help(help) # the same
help(lapply)
?lapply # the same
help("for") # or ?"for", but the quotes are needed
?"+"
help(package = stepfun) # get help even when package is not loaded
data() # list all available data sets
?women # information about data set "women"
topi <- "women"
help(topi) ##--> Error: No documentation for `topi'
try(help("bs", try.all.packages=FALSE)) # reports not found (an error)
help("bs", try.all.packages=TRUE) # reports can be found in package `splines'