% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/citation.R
\name{write_bib}
\alias{write_bib}
\title{Generate BibTeX bibliography databases for R packages}
\usage{
write_bib(
  x = .packages(),
  file = "",
  tweak = TRUE,
  width = NULL,
  prefix = getOption("knitr.bib.prefix", "R-")
)
}
\arguments{
\item{x}{Package names. Packages which are not installed are ignored.}

\item{file}{The (\file{.bib}) file to write. By default, or if \code{NULL},
output is written to the R console.}

\item{tweak}{Whether to fix some known problems in the citations, especially
non-standard format of author names.}

\item{width}{Width of lines in bibliography entries. If \code{NULL}, lines
will not be wrapped.}

\item{prefix}{Prefix string for keys in BibTeX entries; by default, it is
\samp{R-} unless \code{\link{option}('knitr.bib.prefix')} has been set to
another string.}
}
\value{
A list containing the citations. Citations are also written to the
  \code{file} as a side effect.
}
\description{
This function uses \code{\link[utils]{citation}} and
\code{\link[utils]{toBibtex}} to create bib entries for R packages and write
them in a file. It can facilitate the auto-generation of bibliography
databases for R packages, and it is easy to regenerate all the citations
after updating R packages.
}
\details{
For a package, the keyword \samp{R-pkgname} is used for its bib item, where
\samp{pkgname} is the name of the package. Citation entries specified in the
\file{CITATION} file of the package are also included. The main purpose of
this function is to automate the generation of the package citation
information because it often changes (e.g. author, year, package version,
...).
}
\note{
Some packages on CRAN do not have standard bib entries, which was once
  reported by Michael Friendly at
  \url{https://stat.ethz.ch/pipermail/r-devel/2010-November/058977.html}. I
  find this a real pain, and there are no easy solutions except contacting
  package authors to modify their DESCRIPTION files. Anyway, the argument
  \code{tweak} has provided ugly hacks to deal with packages which are known
  to be non-standard in terms of the format of citations; \code{tweak = TRUE}
  is by no means intended to hide or modify the original citation
  information. It is just due to the loose requirements on package authors
  for the DESCRIPTION file. On one hand, I apologize if it really mangles the
  information about certain packages; on the other, I strongly recommend
  package authors to consider the \samp{Authors@R} field (see the manual
  \emph{Writing R Extensions}) to make it easier for other people to cite R
  packages. See \code{knitr:::.tweak.bib} for details of tweaks. Also note
  this is subject to future changes since R packages are being updated. If
  you want to contribute more tweaks, please edit the file
  \file{inst/misc/tweak_bib.csv} in the source package.
}
\examples{
write_bib(c("RGtk2", "gWidgets"), file = "R-GUI-pkgs.bib")
unlink("R-GUI-pkgs.bib")

write_bib(c("animation", "rgl", "knitr", "ggplot2"))
write_bib(c("base", "parallel", "MASS"))  # base and parallel are identical
write_bib("cluster", prefix = "")  # a empty prefix
write_bib("digest", prefix = "R-pkg-")  # a new prefix
write_bib("digest", tweak = FALSE)  # original version

# what tweak=TRUE does
str(knitr:::.tweak.bib)
}
\author{
Yihui Xie and Michael Friendly
}
