Generate BibTeX bibliography databases for R packages

Call utils::citation() and 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.

pkg_bib(
  x = .packages(),
  file = "",
  tweak = TRUE,
  width = NULL,
  prefix = getOption("xfun.bib.prefix", "R-"),
  lib.loc = NULL,
  packageURL = TRUE,
  date = c("none", "package", "today")
)

Arguments

x: Package names. Packages which are not installed are ignored.
file: The (.bib) file to write. By default, or if NULL, output is written to the R console.
tweak: Whether to fix some known problems in the citations, especially non-standard format of author names.
width: Width of lines in bibliography entries. If NULL, lines will not be wrapped.
prefix: Prefix string for keys in BibTeX entries; by default, it is R- unless option('xfun.bib.prefix') has been set to another string.
lib.loc: A vector of path names of R libraries.
packageURL: Use the URL field from the DESCRIPTION file. See Details below.
date: The way to include a date of the form (retrieved YYYY-mm-dd) in the note field of bib entries. For date = 'none', no date is included. For date = 'package', the packageDate() of the package is included. For date = 'today', Sys.Date() is included. Alternatively, you can provide a date directly, e.g., date = '2025-04-01'.

Value

A list containing the citations. Citations are also written to the file as a side effect.

Details

For a package, the keyword R-pkgname is used for its bib item, where pkgname is the name of the package. Citation entries specified in the 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., the author, year, package version, and so on).

There are at least two different uses for the URL in a reference list. You might want to tell users where to go for more information. In that case, use the default packageURL = TRUE, and the first URL listed in the DESCRIPTION file will be used. Be careful: some authors don't put the most relevant URL first. Alternatively, you might want to identify exactly which version of the package was used in the document. If it was installed from CRAN or some other repositories, the version number identifies it, and packageURL = FALSE will use the repository URL (as used by utils::citation()).

Note

Some packages on CRAN do not have standard bib entries, which was once reported by Michael Friendly at https://stat.ethz.ch/pipermail/r-devel/2010-November/058977.html. I find this a pain, and there are no easy solutions except contacting package authors to modify their DESCRIPTION files. The argument tweak has provided hacks to deal with known packages with non-standard bib entries; 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 Authors@R field (see the manual Writing R Extensions) to make it easier for other people to cite R packages.

Author

Yihui Xie and Michael Friendly

Examples

pkg_bib(c("base", "MASS", "xfun"))
#> Warning: could not determine year for ‘xfun’ from package DESCRIPTION file
#> @Manual{R-MASS,
#>   title = {MASS: Support Functions and Datasets for Venables and Ripley's MASS},
#>   author = {Brian Ripley and Bill Venables},
#>   year = {2025},
#>   note = {R package version 7.3-65},
#>   url = {http://www.stats.ox.ac.uk/pub/MASS4/},
#> }
#> 
#> @Manual{R-base,
#>   title = {R: A Language and Environment for Statistical Computing},
#>   author = {{R Core Team}},
#>   organization = {R Foundation for Statistical Computing},
#>   address = {Vienna, Austria},
#>   year = {2025},
#>   url = {https://www.R-project.org/},
#> }
#> 
#> @Manual{R-xfun,
#>   title = {xfun: Supporting Functions for Packages Maintained by Yihui Xie},
#>   author = {Yihui Xie},
#>   note = {R package version 0.54},
#>   url = {https://github.com/yihui/xfun},
#>   year = {2025},
#> }
#> 
#> @Book{MASS2002,
#>   title = {Modern Applied Statistics with S},
#>   author = {W. N. Venables and B. D. Ripley},
#>   publisher = {Springer},
#>   edition = {Fourth},
#>   address = {New York},
#>   year = {2002},
#>   note = {ISBN 0-387-95457-0},
#>   url = {https://www.stats.ox.ac.uk/pub/MASS4/},
#> }
#> 
pkg_bib("cluster", prefix = "R-pkg-")  # a different prefix
#> @Manual{R-pkg-cluster,
#>   title = {cluster: "Finding Groups in Data": Cluster Analysis Extended Rousseeuw et
#> al.},
#>   author = {Martin Maechler and Peter Rousseeuw and Anja Struyf and Mia Hubert},
#>   year = {2025},
#>   note = {R package version 2.1.8.1},
#>   url = {https://svn.r-project.org/R-packages/trunk/cluster/},
#> }
#> 
pkg_bib("xfun", date = "package")
#> Warning: could not determine year for ‘xfun’ from package DESCRIPTION file
#> @Manual{R-xfun,
#>   title = {xfun: Supporting Functions for Packages Maintained by Yihui Xie},
#>   author = {Yihui Xie},
#>   note = {R package version 0.54 (retrieved 2025-11-18)},
#>   url = {https://github.com/yihui/xfun},
#>   year = {2025},
#> }
#>