## Documentation

## Usage

    help(topic, offline = FALSE, package = c(.packages(), .Autoloaded),
         lib.loc = .lib.loc, verbose = .Options$verbose,
          htmlhelp = .Options$htmlhelp)
    ?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. Defaults to all libraries currently known.
`verbose` | logical; if `TRUE`, the file name is reported.
`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.

## 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`. In the case of unary and binary operators and control-flow special forms, the name may need to be 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

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'.

## See Also

`help.start()` which opens the HTML version of the R Manual; `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 it's not present

    data()			# list all available data sets
    ?women			# information about data set "women"

    topi <- "women"
    help(topi) ##--> Error: No documentation for `topi'

[Package Contents]