help {base}

R Documentation

Documentation

Description

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.

Usage

help(topic, offline = FALSE, package = .packages(),
     lib.loc = NULL, verbose = getOption("verbose"),
     try.all.packages = getOption("help.try.all.packages"),
     htmlhelp = getOption("htmlhelp"),
     pager = getOption("pager"))
?topic
type?topic

Arguments

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, or NULL. The default value of NULL corresponds 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 the browser specified by options("browser"). See help.start for details of the browsers that are supported.
pager	the pager to be used for file.show.
type	the special type of documentation to use for this topic; for example, if the type is class, documentation is provided for the class with name topic. The function topicName returns the actual name used in this case.

Details

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.

Note

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 the known library trees, 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 the known library trees 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 that file ‘AnIndex’ remains un-zipped. Similarly, all the files in the ‘latex’ directory can be zipped to ‘Rhelp.zip’.

See Also

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.

Examples

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"
## Not run: 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'

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