% File src/library/tools/man/HTMLlinks.Rd
% Part of the R package, https://www.R-project.org
% Copyright 2009 R Core Team
% Distributed under GPL 2 or later

\name{HTMLlinks}
\alias{findHTMLlinks}
\title{Collect HTML Links from Package Documentation}
\description{
  Compute relative file paths for URLs to other package's installed HTML
  documentation.
}
\usage{
findHTMLlinks(pkgDir = "", lib.loc = NULL, level = 0:3)
}
\arguments{
  \item{pkgDir}{the top-level directory of an installed package.  The
    default indicates no package.}
  \item{lib.loc}{character vector describing the location of \R library
    trees to scan: the default indicates \code{\link{.libPaths}()}.}
  \item{level}{Which level(s) to include.}
}
\details{
  \code{findHTMLlinks} tries to resolve links from one help page to
  another.  It uses in decreasing priority
  \itemize{
    \item The package in \code{pkgDir}: this is used when converting
    HTML help for that package (level 0).
    \item The base and recommended packages (levels 1 and 2).
    \item Other packages found in the library trees specified by
    \code{lib.loc} in the order of the trees and alphabetically within a
    library tree (level 3).
  }
}
\value{
  A named character vector of file paths, relative to the \file{html}
  directory of an installed package.  So these are of the form
  \file{"../../\var{somepkg}/html/\var{sometopic}.html"}.
}
\author{Duncan Murdoch, Brian Ripley}
\keyword{ documentation }
