From R to CFF

This vignette provides an explicit map between the metadata sources used by cffr and each valid key in the Citation File Format schema version 1.2.0.

Summary

This section summarizes the keys that cffr can populate and the metadata source for each one. Details for each key are presented in the next section. The assessment is based on the Guide to Citation File Format schema version 1.2.0 (Druskat et al. 2021).

key	source
abstract	DESCRIPTION file
authors	DESCRIPTION file
cff-version	function argument
commit	DESCRIPTION file
contact	DESCRIPTION file
date-released	DESCRIPTION file
doi	inst/CITATION or CRAN
identifiers	DESCRIPTION, inst/CITATION and CRAN
keywords	DESCRIPTION file
license	DESCRIPTION file
license-url	Ignored by cffr
message	DESCRIPTION file
preferred-citation	inst/CITATION
references	DESCRIPTION and inst/CITATION
repository	DESCRIPTION file
repository-artifact	Ignored by cffr
repository-code	DESCRIPTION file
title	DESCRIPTION file
type	Fixed value: ‘software’
url	DESCRIPTION file
version	DESCRIPTION file

Table 1: cffr and R packages: Conversion table

Details

abstract

This key is extracted from the "Description" field of the DESCRIPTION file.

Example

library(cffr)

# Create a `cff` object for YAML.

cff_obj <- cff_create("rmarkdown")

# Get the DESCRIPTION of **rmarkdown** to check.

pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cat(cff_obj$abstract)
#> Convert R Markdown documents into a variety of formats.

cat(pkg$get("Description"))
#> Convert R Markdown documents into a variety of formats.

Back to Table 1.

authors

This key is coerced from the "Authors" or "Authors@R" field of the DESCRIPTION file. By default, persons with the role "aut" or "cre" are considered, but this can be modified with the authors_roles argument.

Example

# An example DESCRIPTION.
path <- system.file("examples/DESCRIPTION_many_persons", package = "cffr")
pkg <- desc::desc(path)

# See the listed persons.
pkg$get_authors()
#> [1] "Diego Hernangómez <[email protected]> [aut, cre] (ORCID: <https://orcid.org/0000-0001-8457-4658>, email: error, not-valid: error)"
#> [2] "Joe Doe <I am a wrong email> [aut] (affiliation: This One, country: ES, date-end: error)"                                      
#> [3] "Pepe Doe <[email protected]> [aut] (error)"                                                                                       
#> [4] "I am an entity [cre] (date-end: 2020-01-01, affiliation: error)"                                                               
#> [5] "ERROR entity [cph] (for the administrative boundaries.)"                                                                       
#> [6] "ERROR person [cph] (ORCID: <https://orcid.org/0000-0003-2042-7063>, for the gisco_countrycode dataset.)"

# Default behavior: use authors and creators (maintainers).
cff_obj <- cff_create(path)
cff_obj$authors
#> - family-names: Hernangómez
#>   given-names: Diego
#>   email: [email protected]
#>   orcid: https://orcid.org/0000-0001-8457-4658
#> - family-names: Doe
#>   given-names: Joe
#>   affiliation: This One
#>   country: ES
#> - family-names: Doe
#>   given-names: Pepe
#>   email: [email protected]
#> - name: I am an entity
#>   date-end: '2020-01-01'

# Use copyright holders and maintainers.
cff_obj_alt <- cff_create(path, authors_roles = c("cre", "cph"))
cff_obj_alt$authors
#> - family-names: Hernangómez
#>   given-names: Diego
#>   email: [email protected]
#>   orcid: https://orcid.org/0000-0001-8457-4658
#> - name: I am an entity
#>   date-end: '2020-01-01'
#> - name: ERROR entity
#> - family-names: person
#>   given-names: ERROR
#>   orcid: https://orcid.org/0000-0003-2042-7063

Back to Table 1.

cff-version

Set this key with the cff_version argument of cff_create() or cff_write():

Example

cff_objv110 <- cff_create("jsonlite", cff_version = "v1.1.0")

cat(cff_objv110$`cff-version`)
#> v1.1.0

Back to Table 1.

commit

This key is extracted from the "RemoteSha" field of the DESCRIPTION file. This field is present in packages installed from r-universe or with package managers such as remotes and pak.

Example

# An example DESCRIPTION.
path <- system.file("examples/DESCRIPTION_r_universe", package = "cffr")
pkg <- desc::desc(path)

# See `RemoteSha`.
pkg$get("RemoteSha")
#>                                  RemoteSha 
#> "bdd9a29d7eabcc43c3195fe461f884932eba763c"

cff_read(path)
#> cff-version: 1.2.0
#> message: 'To cite package "codemetar" in publications use:'
#> type: software
#> title: 'codemetar: Generate ''CodeMeta'' Metadata for R Packages'
#> version: 0.3.5
#> authors:
#> - family-names: Boettiger
#>   given-names: Carl
#>   email: [email protected]
#>   orcid: https://orcid.org/0000-0002-1642-628X
#> - family-names: Salmon
#>   given-names: Maëlle
#>   orcid: https://orcid.org/0000-0002-2815-0399
#> abstract: The 'Codemeta' Project defines a 'JSON-LD' format for describing software
#>   metadata, as detailed at <https://codemeta.github.io>. This package provides utilities
#>   to generate, parse, and modify 'codemeta.json' files automatically for R packages,
#>   as well as tools and examples for working with 'codemeta.json' 'JSON-LD' more generally.
#> repository: https://ropensci.r-universe.dev
#> repository-code: https://github.com/ropensci/codemetar
#> url: https://docs.ropensci.org/codemetar/
#> date-released: '2024-02-09'
#> contact:
#> - family-names: Boettiger
#>   given-names: Carl
#>   email: [email protected]
#>   orcid: https://orcid.org/0000-0002-1642-628X
#> keywords:
#> - metadata
#> - codemeta
#> - ropensci
#> - citation
#> - credit
#> - linked-data
#> - json-ld
#> - peer-reviewed
#> - r
#> - r-package
#> - rstats
#> license: GPL-3.0-only
#> commit: bdd9a29d7eabcc43c3195fe461f884932eba763c
#> doi: 10.32614/CRAN.package.codemetar

Back to Table 1.

contact

This key is coerced from the "Authors" or "Authors@R" field of the DESCRIPTION file. Only persons with the role "cre" (that is, maintainers) are considered.

Example

cff_obj <- cff_create("rmarkdown")
pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cff_obj$contact
#> - family-names: Xie
#>   given-names: Yihui
#>   email: [email protected]
#>   orcid: https://orcid.org/0000-0003-0645-5666

pkg$get_author()
#> [1] "Yihui Xie <[email protected]> [aut, cre] (ORCID: <https://orcid.org/0000-0003-0645-5666>)"

Back to Table 1.

date-released

This key is extracted from the DESCRIPTION file using this logic:

"Date", when present.
Otherwise, "Date/Publication". This field is present in packages built on CRAN and Bioconductor.
Otherwise, "Packaged", which is present in packages built by r-universe.

Example

# Use an installed package.

cff_obj <- cff_create("rmarkdown")
pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cat(pkg$get("Date/Publication"))
#> 2026-03-26 16:30:02 UTC

cat(cff_obj$`date-released`)
#> 2026-03-26

# A DESCRIPTION file without a `Date`.
nodate <- system.file("examples/DESCRIPTION_basic", package = "cffr")
tmp <- tempfile("DESCRIPTION")

# Create a temporary file.
file.copy(nodate, tmp)
#> [1] TRUE

pkgnodate <- desc::desc(tmp)
cffnodate <- cff_create(tmp)

# No value is returned.
cat(cffnodate$`date-released`)

pkgnodate
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <[email protected]> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

# Add a `Date`.

desc::desc_set("Date", "1999-01-01", file = tmp)
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Date: 1999-01-01
#> Authors@R (parsed):
#>     * Marc Basic <[email protected]> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

cat(cff_create(tmp)$`date-released`)
#> 1999-01-01

Back to Table 1.

doi

This key is coerced from the "doi" field of the preferred-citation object. If it is not present, cffr adds the canonical CRAN DOI only when the package metadata identifies CRAN as its repository or a repository lookup resolves to the canonical CRAN package URL. Finding the package in another configured repository does not produce a CRAN DOI. For example, the canonical DOI for cffr is https://doi.org/10.32614/CRAN.package.cffr.

Example

cff_doi <- cff_create("cffr")

cat(cff_doi$doi)
#> 10.21105/joss.03900

cat(cff_doi$`preferred-citation`$doi)
#> 10.21105/joss.03900

Back to Table 1.

identifiers

This key contains the available package identifiers:

From DESCRIPTION metadata, it includes all the URLs not included in url or repository-code.
From the CITATION file, it includes all the DOIs not included in doi and the identifiers (if any) not included in the "identifiers" key of preferred-citation.
If the package is on CRAN and it has a CITATION file providing a DOI, the DOI provided by CRAN is added as well.

cffr removes identical entries after merging identifiers from these sources.

Example

file <- system.file("examples/DESCRIPTION_many_urls", package = "cffr")

pkg <- desc::desc(file)

cat(pkg$get_urls())
#> https://github.com/test/package https://test.github.io/package/ https://r-forge.r-project.org/projects/test/ http://google.ru https://gitlab.com/r-packages/behaviorchange

cat(cff_create(file)$url)
#> https://test.github.io/package/

cat(cff_create(file)$`repository-code`)
#> https://github.com/test/package

cff_create(file)$identifiers
#> - type: url
#>   value: https://r-forge.r-project.org/projects/test/
#> - type: url
#>   value: http://google.ru
#> - type: url
#>   value: https://gitlab.com/r-packages/behaviorchange

Back to Table 1.

keywords

This key is extracted from the DESCRIPTION file. The keywords should appear in the DESCRIPTION as:

...
X-schema.org-keywords: keyword1, keyword2, keyword3

The comma-separated values are trimmed and empty or duplicate values are removed. A single keyword is preserved as a one-item CFF keywords array.

Example

# A DESCRIPTION file without keywords
nokeywords <- system.file("examples/DESCRIPTION_basic", package = "cffr")
tmp2 <- tempfile("DESCRIPTION")

# Create a temporary file.
file.copy(nokeywords, tmp2)
#> [1] TRUE

pkgnokeywords <- desc::desc(tmp2)
cffnokeywords <- cff_create(tmp2)

# No value is returned.
cat(cffnokeywords$keywords)

pkgnokeywords
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <[email protected]> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

# Add keywords.

desc::desc_set(
  "X-schema.org-keywords",
  "keyword1, keyword2, keyword3",
  file = tmp2
)
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <[email protected]> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000
#> X-schema.org-keywords: keyword1, keyword2, keyword3

cat(cff_create(tmp2)$keywords)
#> keyword1 keyword2 keyword3

If the package source code is hosted on GitHub, cffr can also retrieve repository topics with the GitHub API and include those topics as keywords. This option is controlled with the gh_keywords argument:

Example

# Get a `cff` object from **jsonvalidate**.

jsonval <- cff_create("jsonvalidate")

# Keywords are retrieved from the **GitHub** repository.

jsonval
#> cff-version: 1.2.0
#> message: 'To cite package "jsonvalidate" in publications use:'
#> type: software
#> license: MIT
#> title: 'jsonvalidate: Validate ''JSON'' Schema'
#> version: 1.5.0
#> doi: 10.32614/CRAN.package.jsonvalidate
#> abstract: Uses the node library 'is-my-json-valid' or 'ajv' to validate 'JSON' against
#>   a 'JSON' schema. Drafts 04, 06 and 07 of 'JSON' schema are supported.
#> authors:
#> - family-names: FitzJohn
#>   given-names: Rich
#>   email: [email protected]
#> - family-names: Ashton
#>   given-names: Rob
#> - family-names: Buus
#>   given-names: Mathias
#> - family-names: Poberezkin
#>   given-names: Evgeny
#> repository: https://ropensci.r-universe.dev
#> repository-code: https://github.com/ropensci/jsonvalidate
#> commit: 01868830ce88f6e44fec8d86f3e3185cb4f16352
#> url: https://docs.ropensci.org/jsonvalidate/
#> date-released: '2025-02-07'
#> contact:
#> - family-names: FitzJohn
#>   given-names: Rich
#>   email: [email protected]
#> keywords:
#> - json
#> - json-validation
#> - jsonvalidate
#> - r
#> - r-package
#> - rstats
#> references:
#> - type: software
#>   title: 'R6: Encapsulated Classes with Reference Semantics'
#>   notes: Imports
#>   url: https://r6.r-lib.org
#>   repository: https://CRAN.R-project.org/package=R6
#>   authors:
#>   - family-names: Chang
#>     given-names: Winston
#>     email: [email protected]
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.R6
#> - type: software
#>   title: 'V8: Embedded JavaScript and WebAssembly Engine for R'
#>   notes: Imports
#>   url: https://jeroen.r-universe.dev/V8
#>   repository: https://CRAN.R-project.org/package=V8
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.V8
#> - type: software
#>   title: 'knitr: A General-Purpose Package for Dynamic Report Generation in R'
#>   notes: Suggests
#>   url: https://yihui.org/knitr/
#>   repository: https://CRAN.R-project.org/package=knitr
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.knitr
#> - type: software
#>   title: 'jsonlite: A Simple and Robust JSON Parser and Generator for R'
#>   notes: Suggests
#>   url: https://jeroen.r-universe.dev/jsonlite
#>   repository: https://CRAN.R-project.org/package=jsonlite
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.jsonlite
#> - type: software
#>   title: 'rmarkdown: Dynamic Documents for R'
#>   notes: Suggests
#>   url: https://pkgs.rstudio.com/rmarkdown/
#>   repository: https://CRAN.R-project.org/package=rmarkdown
#>   authors:
#>   - family-names: Allaire
#>     given-names: JJ
#>     email: [email protected]
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   - family-names: Dervieux
#>     given-names: Christophe
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-4474-2498
#>   - family-names: McPherson
#>     given-names: Jonathan
#>     email: [email protected]
#>   - family-names: Luraschi
#>     given-names: Javier
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: [email protected]
#>   - family-names: Atkins
#>     given-names: Aron
#>     email: [email protected]
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: [email protected]
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: [email protected]
#>   - family-names: Chang
#>     given-names: Winston
#>     email: [email protected]
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.rmarkdown
#> - type: software
#>   title: 'testthat: Unit Testing for R'
#>   notes: Suggests
#>   url: https://testthat.r-lib.org
#>   repository: https://CRAN.R-project.org/package=testthat
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: [email protected]
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.testthat
#> - type: software
#>   title: 'withr: Run Code ''With'' Temporarily Modified Global State'
#>   notes: Suggests
#>   url: https://withr.r-lib.org
#>   repository: https://CRAN.R-project.org/package=withr
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: [email protected]
#>   - family-names: Müller
#>     given-names: Kirill
#>     email: [email protected]
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: [email protected]
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: [email protected]
#>   - family-names: Chang
#>     given-names: Winston
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.withr

# Check keywords.
jsonval$keywords
#> [1] "json"            "json-validation" "jsonvalidate"    "r"              
#> [5] "r-package"       "rstats"

# The repository.
jsonval$`repository-code`
#> [1] "https://github.com/ropensci/jsonvalidate"

Back to Table 1.

license

This key is extracted from the "License" field of the DESCRIPTION file. All alternatives recognized by the cran_to_spdx mapping are preserved.

Example

cff_obj <- cff_create("yaml")

cat(cff_obj$license)
#> BSD-3-Clause

pkg <- desc::desc(file.path(find.package("yaml"), "DESCRIPTION"))

cat(pkg$get("License"))
#> BSD_3_clause + file LICENSE

Back to Table 1.

license-url

This key is not extracted from package metadata. See its description in the Guide to CFF schema v1.2.0.

description: The URL of the license text under which the software or dataset is licensed (only for non-standard licenses not included in the SPDX License List).
usage:
license-url: "https://obscure-licenses.com?id=1234"

Back to Table 1.

message

This key is generated from the package metadata with this template:

msg <- paste0(
  'To cite package "',
  "NAME_OF_THE_PACKAGE",
  '" in publications use:'
)

Example

cat(cff_create("jsonlite")$message)
#> To cite package "jsonlite" in publications use:

Back to Table 1.

preferred-citation

This key is extracted from inst/CITATION. When cff_create() reads this file, all fields from DESCRIPTION, including custom fields, are available through the meta object used by the CITATION file. If multiple references are provided, cffr selects the first citation as "preferred-citation" and uses the remaining citations as references. If the file cannot be read with the package metadata, cffr does not retry with metadata from another package.

Example

cffobj <- cff_create("rmarkdown")

cffobj$`preferred-citation`
#> type: manual
#> title: 'rmarkdown: Dynamic Documents for R'
#> authors:
#> - family-names: Allaire
#>   given-names: JJ
#>   email: [email protected]
#> - family-names: Xie
#>   given-names: Yihui
#>   email: [email protected]
#>   orcid: https://orcid.org/0000-0003-0645-5666
#> - family-names: Dervieux
#>   given-names: Christophe
#>   email: [email protected]
#>   orcid: https://orcid.org/0000-0003-4474-2498
#> - family-names: McPherson
#>   given-names: Jonathan
#>   email: [email protected]
#> - family-names: Luraschi
#>   given-names: Javier
#> - family-names: Ushey
#>   given-names: Kevin
#>   email: [email protected]
#> - family-names: Atkins
#>   given-names: Aron
#>   email: [email protected]
#> - family-names: Wickham
#>   given-names: Hadley
#>   email: [email protected]
#> - family-names: Cheng
#>   given-names: Joe
#>   email: [email protected]
#> - family-names: Chang
#>   given-names: Winston
#>   email: [email protected]
#> - family-names: Iannone
#>   given-names: Richard
#>   email: [email protected]
#>   orcid: https://orcid.org/0000-0003-3925-190X
#> year: '2026'
#> notes: R package version 2.31
#> url: https://github.com/rstudio/rmarkdown

citation("rmarkdown")[1]
#> Allaire J, Xie Y, Dervieux C, McPherson J, Luraschi J, Ushey K, Atkins
#> A, Wickham H, Cheng J, Chang W, Iannone R (2026). _rmarkdown: Dynamic
#> Documents for R_. R package version 2.31,
#> <https://github.com/rstudio/rmarkdown>.
#> 
#> A BibTeX entry for LaTeX users is
#> 
#>   @Manual{,
#>     title = {rmarkdown: Dynamic Documents for R},
#>     author = {JJ Allaire and Yihui Xie and Christophe Dervieux and Jonathan McPherson and Javier Luraschi and Kevin Ushey and Aron Atkins and Hadley Wickham and Joe Cheng and Winston Chang and Richard Iannone},
#>     year = {2026},
#>     note = {R package version 2.31},
#>     url = {https://github.com/rstudio/rmarkdown},
#>   }

Back to Table 1.

references

This key is extracted from inst/CITATION if multiple references are provided. The first citation becomes the preferred citation and the remaining citations become "references".

When dependencies = TRUE, cffr also adds installed package dependencies by calling citation(auto = TRUE) for each one. It preserves the citation metadata, including the title, abstract, authors and year, while adapting the reference to the CFF software type. It adds the dependency scope and version constraint from the source DESCRIPTION, URLs and repository information from the installed dependency’s DESCRIPTION and the canonical CRAN DOI only when the dependency is available from CRAN. A release date, when available, determines the year, with the year returned by citation() retained otherwise. The year is omitted only when neither source provides one.

Example

cffobj <- cff_create("rmarkdown")

cffobj$references
#> - type: book
#>   title: 'R Markdown: The Definitive Guide'
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>   - family-names: Allaire
#>     given-names: J.J.
#>   - family-names: Grolemund
#>     given-names: Garrett
#>   publisher:
#>     name: Chapman and Hall/CRC
#>     address: Boca Raton, Florida
#>   year: '2018'
#>   isbn: '9781138359338'
#>   url: https://yihui.org/rmarkdown/
#> - type: book
#>   title: R Markdown Cookbook
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>   - family-names: Dervieux
#>     given-names: Christophe
#>   - family-names: Riederer
#>     given-names: Emily
#>   publisher:
#>     name: Chapman and Hall/CRC
#>     address: Boca Raton, Florida
#>   year: '2020'
#>   isbn: '9780367563837'
#>   url: https://yihui.org/rmarkdown-cookbook
#> - type: software
#>   title: 'R: A Language and Environment for Statistical Computing'
#>   notes: Depends
#>   url: https://www.R-project.org/
#>   authors:
#>   - name: R Core Team
#>     website: https://ror.org/02zz1nj61
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     website: https://ror.org/05qewa988
#>     address: Vienna, Austria
#>   year: '2026'
#>   doi: 10.32614/R.manuals
#>   version: '>= 3.0'
#> - type: software
#>   title: 'bslib: Custom ''Bootstrap'' ''Sass'' Themes for ''shiny'' and ''rmarkdown'''
#>   notes: Imports
#>   url: https://rstudio.github.io/bslib/
#>   repository: https://CRAN.R-project.org/package=bslib
#>   authors:
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: [email protected]
#>   - family-names: Aden-Buie
#>     given-names: Garrick
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-7111-0077
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.bslib
#>   version: '>= 0.2.5.1'
#> - type: software
#>   title: 'evaluate: Parsing and Evaluation Tools that Provide More Details than the
#>     Default'
#>   notes: Imports
#>   url: https://evaluate.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=evaluate
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: [email protected]
#>   - family-names: Xie
#>     given-names: Yihui
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.evaluate
#>   version: '>= 0.13'
#> - type: software
#>   title: 'fontawesome: Easily Work with ''Font Awesome'' Icons'
#>   notes: Imports
#>   url: https://rstudio.github.io/fontawesome/
#>   repository: https://CRAN.R-project.org/package=fontawesome
#>   authors:
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   year: '2024'
#>   doi: 10.32614/CRAN.package.fontawesome
#>   version: '>= 0.5.0'
#> - type: software
#>   title: 'htmltools: Tools for HTML'
#>   notes: Imports
#>   url: https://rstudio.github.io/htmltools/
#>   repository: https://CRAN.R-project.org/package=htmltools
#>   authors:
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: [email protected]
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Schloerke
#>     given-names: Barret
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0001-9986-114X
#>   - family-names: Chang
#>     given-names: Winston
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-1576-2126
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: [email protected]
#>   - family-names: Allen
#>     given-names: Jeff
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.htmltools
#>   version: '>= 0.5.1'
#> - type: software
#>   title: 'jquerylib: Obtain ''jQuery'' as an HTML Dependency Object'
#>   notes: Imports
#>   repository: https://CRAN.R-project.org/package=jquerylib
#>   authors:
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: [email protected]
#>   year: '2021'
#>   doi: 10.32614/CRAN.package.jquerylib
#> - type: software
#>   title: 'jsonlite: A Simple and Robust JSON Parser and Generator for R'
#>   notes: Imports
#>   url: https://jeroen.r-universe.dev/jsonlite
#>   repository: https://CRAN.R-project.org/package=jsonlite
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.jsonlite
#> - type: software
#>   title: 'knitr: A General-Purpose Package for Dynamic Report Generation in R'
#>   notes: Imports
#>   url: https://yihui.org/knitr/
#>   repository: https://CRAN.R-project.org/package=knitr
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.knitr
#>   version: '>= 1.43'
#> - type: software
#>   title: 'R: A Language and Environment for Statistical Computing'
#>   notes: Imports
#>   authors:
#>   - name: R Core Team
#>     website: https://ror.org/02zz1nj61
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     website: https://ror.org/05qewa988
#>     address: Vienna, Austria
#>   year: '2026'
#>   doi: 10.32614/R.manuals
#> - type: software
#>   title: 'tinytex: Helper Functions to Install and Maintain TeX Live, and Compile
#>     LaTeX Documents'
#>   notes: Imports
#>   url: https://github.com/rstudio/tinytex
#>   repository: https://CRAN.R-project.org/package=tinytex
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.tinytex
#>   version: '>= 0.31'
#> - type: software
#>   title: 'xfun: Supporting Functions for Packages Maintained by ''Yihui Xie'''
#>   notes: Imports
#>   url: https://github.com/yihui/xfun
#>   repository: https://CRAN.R-project.org/package=xfun
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.xfun
#>   version: '>= 0.36'
#> - type: software
#>   title: 'yaml: Methods to Convert R Data to YAML and Back'
#>   notes: Imports
#>   url: https://yaml.r-lib.org
#>   repository: https://CRAN.R-project.org/package=yaml
#>   authors:
#>   - family-names: Stephens
#>     given-names: Jeremy
#>   - family-names: Simonov
#>     given-names: Kirill
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.yaml
#>   version: '>= 2.1.19'
#> - type: software
#>   title: 'digest: Create Compact Hash Digests of R Objects'
#>   notes: Suggests
#>   url: https://eddelbuettel.github.io/digest/
#>   repository: https://CRAN.R-project.org/package=digest
#>   authors:
#>   - family-names: Eddelbuettel
#>     given-names: Dirk
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0001-6419-907X
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.digest
#> - type: software
#>   title: 'fs: Cross-Platform File System Operations Based on ''libuv'''
#>   notes: Suggests
#>   url: https://fs.r-lib.org
#>   repository: https://CRAN.R-project.org/package=fs
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Wickham
#>     given-names: Hadley
#>   - family-names: Csárdi
#>     given-names: Gábor
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.fs
#> - type: software
#>   title: 'downlit: Syntax Highlighting and Automatic Linking'
#>   notes: Suggests
#>   url: https://downlit.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=downlit
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: [email protected]
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.downlit
#>   version: '>= 0.4.0'
#> - type: software
#>   title: 'katex: Rendering Math to HTML, ''MathML'', or R-Documentation Format'
#>   notes: Suggests
#>   url: https://docs.ropensci.org/katex/
#>   repository: https://CRAN.R-project.org/package=katex
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2024'
#>   doi: 10.32614/CRAN.package.katex
#>   version: '>= 1.4.0'
#> - type: software
#>   title: 'sass: Syntactically Awesome Style Sheets (''Sass'')'
#>   notes: Suggests
#>   url: https://rstudio.github.io/sass/
#>   repository: https://CRAN.R-project.org/package=sass
#>   authors:
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: [email protected]
#>   - family-names: Mastny
#>     given-names: Timothy
#>     email: [email protected]
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   - family-names: Schloerke
#>     given-names: Barret
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0001-9986-114X
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: [email protected]
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   year: '2025'
#>   doi: 10.32614/CRAN.package.sass
#>   version: '>= 0.4.0'
#> - type: software
#>   title: 'testthat: Unit Testing for R'
#>   notes: Suggests
#>   url: https://testthat.r-lib.org
#>   repository: https://CRAN.R-project.org/package=testthat
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: [email protected]
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.testthat
#>   version: '>= 3.0.3'
#> - type: software
#>   title: 'vctrs: Vector Helpers'
#>   notes: Suggests
#>   url: https://vctrs.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=vctrs
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: [email protected]
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: [email protected]
#>   - family-names: Vaughan
#>     given-names: Davis
#>     email: [email protected]
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.vctrs
#> - type: software
#>   title: 'withr: Run Code ''With'' Temporarily Modified Global State'
#>   notes: Suggests
#>   url: https://withr.r-lib.org
#>   repository: https://CRAN.R-project.org/package=withr
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: [email protected]
#>   - family-names: Müller
#>     given-names: Kirill
#>     email: [email protected]
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: [email protected]
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: [email protected]
#>   - family-names: Chang
#>     given-names: Winston
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.withr
#>   version: '>= 2.4.2'
#> - type: software
#>   title: 'xml2: Parse XML'
#>   notes: Suggests
#>   url: https://xml2.r-lib.org
#>   repository: https://CRAN.R-project.org/package=xml2
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: [email protected]
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.xml2

citation("rmarkdown")[-1]
#> Xie Y, Allaire J, Grolemund G (2018). _R Markdown: The Definitive
#> Guide_. Chapman and Hall/CRC, Boca Raton, Florida. ISBN 9781138359338.
#> <https://yihui.org/rmarkdown/>.
#> 
#> Xie Y, Dervieux C, Riederer E (2020). _R Markdown Cookbook_. Chapman
#> and Hall/CRC, Boca Raton, Florida. ISBN 9780367563837.
#> <https://yihui.org/rmarkdown-cookbook>.
#> 
#> To see these entries in BibTeX format, use 'print(<citation>,
#> bibtex=TRUE)', 'toBibtex(.)', or set
#> 'options(citation.bibtex.max=999)'.

Back to Table 1.

repository

This key is extracted from the "Repository" field of the DESCRIPTION file. This field is usually populated when a package is hosted in a repository such as CRAN or r-universe. For packages without this field in the DESCRIPTION (which is the typical case for an in-development package), cffr tries to find the package in any of the default repositories specified in options("repos").

Bioconductor packages are identified when the "biocViews" field is present in the DESCRIPTION file.

If cffr detects that the package is available on CRAN, it returns the canonical URL form of the package (that is, https://CRAN.R-project.org/package=jsonlite).

Example

# Use an installed package.

inst <- cff_create("jsonlite")

cat(inst$repository)
#> https://CRAN.R-project.org/package=jsonlite

# Demo file downloaded from the r-universe.

runiv <- system.file("examples/DESCRIPTION_r_universe", package = "cffr")
runiv_cff <- cff_create(runiv)

cat(runiv_cff$repository)
#> https://ropensci.r-universe.dev

desc::desc(runiv)$get("Repository")
#>                        Repository 
#> "https://ropensci.r-universe.dev"

# For an in-development package.

norepo <- system.file("examples/DESCRIPTION_basic", package = "cffr")

# No repository is available.
norepo_cff <- cff_create(norepo)

cat(norepo_cff[["repository"]])

# Change the name to a known package on CRAN: ggplot2.

tmp <- tempfile("DESCRIPTION")
file.copy(norepo, tmp)
#> [1] TRUE

# Change the package name.
desc::desc_set("Package", "ggplot2", file = tmp)
#> Type: Package
#> Package: ggplot2
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <[email protected]> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

cat(cff_create(tmp)[["repository"]])
#> https://CRAN.R-project.org/package=ggplot2

Back to Table 1.

repository-artifact

This key is not extracted from package metadata. See its description in the Guide to CFF schema v1.2.0.

description: The URL of the work in a build artifact/binary repository (when the work is software).
usage:
repository-artifact: "https://search.maven.org/artifact/org.corpus-tools/cff-maven-plugin/0.4.0/maven-plugin"

Back to Table 1.

repository-code

This key is extracted from the "BugReports" or "URL" fields in the DESCRIPTION file. cffr tries to identify the URL of the source on the following repositories:

Example

# Installed package on GitHub.

cat(cff_create("jsonlite")$`repository-code`)
#> https://github.com/jeroen/jsonlite

# GitLab

gitlab <- system.file("examples/DESCRIPTION_gitlab", package = "cffr")

cat(cff_create(gitlab)$`repository-code`)
#> https://gitlab.com/ninijay/methoden

# Codeberg
codeberg <- system.file("examples/DESCRIPTION_codeberg", package = "cffr")

cat(cff_create(codeberg)$`repository-code`)
#> https://codeberg.org/dgkf/options

Back to Table 1.

title

This key combines the "Package" and "Title" fields of the DESCRIPTION file.

title <- paste0("NAME_OF_THE_PACKAGE", ": ", "TITLE_OF_THE_PACKAGE")

Example

# Use an installed package.

cat(cff_create("testthat")$title)
#> testthat: Unit Testing for R

Back to Table 1.

type

This key has the fixed value "software". The other valid value is "dataset". See the Guide to CFF schema v1.2.0.

Back to Table 1.

url

This key is extracted from the "BugReports" or "URL" fields in the DESCRIPTION file. It corresponds to the first URL that is different from repository-code.

Example

# Many URLs.
manyurls <- system.file("examples/DESCRIPTION_many_urls", package = "cffr")

cat(cff_create(manyurls)$url)
#> https://test.github.io/package/

# Check the source metadata.

desc::desc(manyurls)
#> Type: Package
#> Package: manyurls
#> Title: A lot of urls
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <[email protected]> [aut, cre, cph]
#> Description: This package has many urls. Specifically, 1 Bug Reports and 6
#>     URLs. Expected is to have 1 repository-code, 1 url and 3 URLs, since
#>     there is 1 duplicate and 1 invalid url.
#> License: GPL-3
#> URL: https://github.com/test/package, https://test.github.io/package/,
#>     https://r-forge.r-project.org/projects/test/, http://google.ru,
#>     https://gitlab.com/r-packages/behaviorchange, this.is.not.an.url
#> BugReports: https://github.com/test/package/issues
#> Encoding: UTF-8

Back to Table 1.

version

This key is extracted from the "Version" field in the DESCRIPTION file.

# Should be (>= 3.0.0).
cat(cff_create("testthat")$version)
#> 3.3.2

Back to Table 1.

References

Druskat, Stephan, Jurriaan H. Spaaks, Neil Chue Hong, et al. 2021. Citation File Format. Version 1.2.0. Zenodo. https://doi.org/10.5281/zenodo.5171937.