The R Project SVN R

\name{help}
\title{Documentation}
\usage{
help(topic, offline = FALSE, package = .packages()
     lib.loc = .lib.loc, verbose = getOption("verbose"),
#ifdef unix
     htmlhelp = getOption("htmlhelp"))
#endif
#ifdef windows
     chmhelp = getOption("chmhelp"),
     htmlhelp = getOption("htmlhelp"), winhelp = getOption("winhelp"))
#endif
?topic
}
\alias{help}
\alias{?}
\arguments{
 \item{topic}{a name or character string on which documentation is
   sought (but \emph{not} a variable containing a character string!).}
 \item{offline}{a logical indicating whether documentation should be
   displayed on-line to the screen (the default) or hardcopy of it
   should be produced.}
 \item{package}{a name or character vector giving the packages to look
   into for documentation.  By default, all packages in the search path
   are used.}
 \item{lib.loc}{A character vector of directory names of \R libraries.
   Defaults to all libraries currently known.}
 \item{verbose}{logical; if \code{TRUE}, the file name is reported.}
#ifdef unix
 \item{htmlhelp}{logical (or \code{NULL}).  If \code{TRUE} (which is the
     default after \code{\link{help.start}} has been called), the HTML
     version of the help will be shown in a browser.}
#endif
#ifdef windows
  \item{chmhelp}{logical (or \code{NULL}).  If \code{TRUE} the
    Compiled HTML version of the help will be shown in a help viewer.}
  \item{htmlhelp}{logical (or \code{NULL}).  If \code{TRUE}, the HTML
    version of the help will be shown in a browser.}
  \item{winhelp}{logical (or \code{NULL}).  If \code{TRUE}, a Windows
    \code{.hlp} file will be used if one is available.}
#endif
}
\description{
  These functions provide access to documentation.
  Documentation on a topic with name \code{name} (typically, an \R
  object or a data set) can be printed with either \code{help(name)} or
  \code{?name}.
}
\details{
  In the case of unary and binary operators and control-flow special
  forms, the name may need to be quoted.

#ifdef unix
  If \code{offline} is \code{TRUE}, hardcopy of the documentation is
  produced by running the LaTeX version of the help page through
  \code{latex} (note that LaTeX 2e is needed) and \code{dvips}.
  Depending on your \code{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 \code{latexcmd} and \code{dvipscmd}, or the environment
  variables \code{R_LATEXCMD} and \code{R_DVIPSCMD} appropriately.
  The appearance of the output can be customized through a file
  \file{Rhelp.cfg} somewhere in your LaTeX search path.
#endif
#ifdef windows
  If \code{offline} is \code{TRUE}, hardcopy of the documentation is
  produced by running the LaTeX version of the help page through
  \code{latex} (note that LaTeX 2e is needed). You need to customize
  the file \file{R\_HOME/bin/helpPRINT.bat} which contains an example.
  The appearance of the output can be customized through a file
  \file{Rhelp.cfg} somewhere in your LaTeX search path.
#endif
}
\note{
  You will only get help for \R objects in your
  \code{\link{search}()} path, i.e., \code{help(dist)} will only work after
  \code{\link{library}(mva)}. To look in all the packages in all the
  current libraries, use
  \code{help(topic, package=.packages(all=T), lib.loc=.lib.loc)}

  The help files can be many small files. On some file systems it is
  desirable to save space, and the text files in the \file{help} directory
  of an installed package can be zipped up as a zip archive
  \file{Rhelp.zip}. Ensure the files \file{AnIndex} and
  \file{00Titles} remain un-zipped.  Similarly, all the files in the
  \file{latex} directory can be zipped to \file{Rhelp.zip}.
}
\seealso{
  \code{\link{help.search}()} for finding help pages on a ``vague'' topic.
  \code{\link{help.start}()} which opens the HTML version of the \R
  Manual;
  \code{\link{library}()} for listing available packages and the
  user-level objects they contain;
  \code{\link{data}()} for listing available data sets;
  \code{\link{methods}()}.

  See \code{\link{prompt}()} to get a prototype for writing \code{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"
\dontrun{help(topi) ##--> Error: No documentation for `topi'}
}
\keyword{documentation}