diff --git a/.Rbuildignore b/.Rbuildignore
index 8f24e66..0a55b50 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -14,3 +14,5 @@
 ^.github
 ^\.github$
 ^codecov\.yml$
+^CITATION\.cff$
+^codemeta\.json$
diff --git a/CITATION.cff b/CITATION.cff
new file mode 100644
index 0000000..9196d22
--- /dev/null
+++ b/CITATION.cff
@@ -0,0 +1,344 @@
+# -----------------------------------------------------------
+# CITATION file created with {cffr} R package, v0.5.0
+# See also: https://docs.ropensci.org/cffr/
+# -----------------------------------------------------------
+ 
+cff-version: 1.2.0
+message: 'To cite package "cartography" in publications use:'
+type: software
+license: GPL-3.0-only
+title: 'cartography: Thematic Cartography'
+version: 3.1.4
+doi: 10.21105/joss.00054
+abstract: Create and integrate maps in your R workflow. This package helps to design
+  cartographic representations such as proportional symbols, choropleth, typology,
+  flows or discontinuities maps. It also offers several features that improve the
+  graphic presentation of maps, for instance, map palettes, layout elements (scale,
+  north arrow, title...), labels or legends. See Giraud and Lambert (2017) <doi:10.1007/978-3-319-57336-6_13>.
+authors:
+- family-names: Giraud
+  given-names: Timothée
+  email: timothee.giraud@cnrs.fr
+  orcid: https://orcid.org/0000-0002-1932-3323
+- family-names: Lambert
+  given-names: Nicolas
+  email: nicolas.lambert@cnrs.fr
+preferred-citation:
+  type: article
+  title: 'cartography: Create and Integrate Maps in your R Workflow'
+  authors:
+  - family-names: Giraud
+    given-names: Timothée
+    email: timothee.giraud@cnrs.fr
+    orcid: https://orcid.org/0000-0002-1932-3323
+  - family-names: Lambert
+    given-names: Nicolas
+    email: nicolas.lambert@cnrs.fr
+  doi: 10.21105/joss.00054
+  url: http://dx.doi.org/10.21105/joss.00054
+  year: '2016'
+  month: '8'
+  publisher:
+    name: The Open Journal
+  volume: '1'
+  issue: '4'
+  journal: JOSS
+repository: https://CRAN.R-project.org/package=cartography
+repository-code: https://github.com/riatelab/cartography/issues/
+url: https://github.com/riatelab/cartography/
+contact:
+- family-names: Giraud
+  given-names: Timothée
+  email: timothee.giraud@cnrs.fr
+  orcid: https://orcid.org/0000-0002-1932-3323
+references:
+- type: conference-paper
+  title: Reproducible Cartography
+  authors:
+  - family-names: Giraud
+    given-names: Timothée
+  - family-names: Lambert
+    given-names: Nicolas
+  collection-title: Advances in Cartography and GIScience. ICACI 2017. Lecture Notes
+    in Geoinformation and Cartography.
+  editors:
+  - family-names: Peterson
+    given-names: Michael
+  section: '13'
+  publisher:
+    name: Springer
+  location:
+    name: Cham, Switzerland
+  year: '2017'
+  doi: 10.1007/978-3-319-57336-6_13
+  start: 173-183
+- type: software
+  title: 'R: A Language and Environment for Statistical Computing'
+  notes: Depends
+  url: https://www.R-project.org/
+  authors:
+  - name: R Core Team
+  location:
+    name: Vienna, Austria
+  year: '2023'
+  institution:
+    name: R Foundation for Statistical Computing
+  version: '>= 3.5.0'
+- type: software
+  title: classInt
+  abstract: 'classInt: Choose Univariate Class Intervals'
+  notes: Imports
+  url: https://r-spatial.github.io/classInt/
+  repository: https://CRAN.R-project.org/package=classInt
+  authors:
+  - family-names: Bivand
+    given-names: Roger
+    email: Roger.Bivand@nhh.no
+    orcid: https://orcid.org/0000-0003-2392-6140
+  year: '2023'
+- type: software
+  title: curl
+  abstract: 'curl: A Modern and Flexible Web Client for R'
+  notes: Imports
+  url: https://jeroen.r-universe.dev/curl
+  repository: https://CRAN.R-project.org/package=curl
+  authors:
+  - family-names: Ooms
+    given-names: Jeroen
+    email: jeroen@berkeley.edu
+    orcid: https://orcid.org/0000-0002-4035-0289
+  year: '2023'
+- type: software
+  title: graphics
+  abstract: 'R: A Language and Environment for Statistical Computing'
+  notes: Imports
+  authors:
+  - name: R Core Team
+  location:
+    name: Vienna, Austria
+  year: '2023'
+  institution:
+    name: R Foundation for Statistical Computing
+- type: software
+  title: methods
+  abstract: 'R: A Language and Environment for Statistical Computing'
+  notes: Imports
+  authors:
+  - name: R Core Team
+  location:
+    name: Vienna, Austria
+  year: '2023'
+  institution:
+    name: R Foundation for Statistical Computing
+- type: software
+  title: png
+  abstract: 'png: Read and write PNG images'
+  notes: Imports
+  url: http://www.rforge.net/png/
+  repository: https://CRAN.R-project.org/package=png
+  authors:
+  - family-names: Urbanek
+    given-names: Simon
+    email: Simon.Urbanek@r-project.org
+  year: '2023'
+- type: software
+  title: raster
+  abstract: 'raster: Geographic Data Analysis and Modeling'
+  notes: Imports
+  url: https://rspatial.org/raster
+  repository: https://CRAN.R-project.org/package=raster
+  authors:
+  - family-names: Hijmans
+    given-names: Robert J.
+    email: r.hijmans@gmail.com
+    orcid: https://orcid.org/0000-0001-5872-2872
+  year: '2023'
+- type: software
+  title: Rcpp
+  abstract: 'Rcpp: Seamless R and C++ Integration'
+  notes: Imports
+  url: https://www.rcpp.org
+  repository: https://CRAN.R-project.org/package=Rcpp
+  authors:
+  - family-names: Eddelbuettel
+    given-names: Dirk
+  - family-names: Francois
+    given-names: Romain
+  - family-names: Allaire
+    given-names: JJ
+  - family-names: Ushey
+    given-names: Kevin
+  - family-names: Kou
+    given-names: Qiang
+  - family-names: Russell
+    given-names: Nathan
+  - family-names: Ucar
+    given-names: Inaki
+  - family-names: Bates
+    given-names: Douglas
+  - family-names: Chambers
+    given-names: John
+  year: '2023'
+- type: software
+  title: sf
+  abstract: 'sf: Simple Features for R'
+  notes: Imports
+  url: https://r-spatial.github.io/sf/
+  repository: https://CRAN.R-project.org/package=sf
+  authors:
+  - family-names: Pebesma
+    given-names: Edzer
+    email: edzer.pebesma@uni-muenster.de
+    orcid: https://orcid.org/0000-0001-8049-7069
+  year: '2023'
+- type: software
+  title: sp
+  abstract: 'sp: Classes and Methods for Spatial Data'
+  notes: Imports
+  url: https://github.com/edzer/sp/
+  repository: https://CRAN.R-project.org/package=sp
+  authors:
+  - family-names: Pebesma
+    given-names: Edzer
+    email: edzer.pebesma@uni-muenster.de
+  - family-names: Bivand
+    given-names: Roger
+    email: Roger.Bivand@nhh.no
+  year: '2023'
+- type: software
+  title: stats
+  abstract: 'R: A Language and Environment for Statistical Computing'
+  notes: Imports
+  authors:
+  - name: R Core Team
+  location:
+    name: Vienna, Austria
+  year: '2023'
+  institution:
+    name: R Foundation for Statistical Computing
+- type: software
+  title: utils
+  abstract: 'R: A Language and Environment for Statistical Computing'
+  notes: Imports
+  authors:
+  - name: R Core Team
+  location:
+    name: Vienna, Austria
+  year: '2023'
+  institution:
+    name: R Foundation for Statistical Computing
+- type: software
+  title: grDevices
+  abstract: 'R: A Language and Environment for Statistical Computing'
+  notes: Imports
+  authors:
+  - name: R Core Team
+  location:
+    name: Vienna, Austria
+  year: '2023'
+  institution:
+    name: R Foundation for Statistical Computing
+- type: software
+  title: lwgeom
+  abstract: 'lwgeom: Bindings to Selected ''liblwgeom'' Functions for Simple Features'
+  notes: Suggests
+  url: https://github.com/r-spatial/lwgeom/
+  repository: https://CRAN.R-project.org/package=lwgeom
+  authors:
+  - family-names: Pebesma
+    given-names: Edzer
+    email: edzer.pebesma@uni-muenster.de
+    orcid: https://orcid.org/0000-0001-8049-7069
+  year: '2023'
+- type: software
+  title: SpatialPosition
+  abstract: 'SpatialPosition: Spatial Position Models'
+  notes: Suggests
+  url: https://github.com/riatelab/SpatialPosition
+  repository: https://CRAN.R-project.org/package=SpatialPosition
+  authors:
+  - family-names: Giraud
+    given-names: Timothée
+    email: timothee.giraud@cnrs.fr
+    orcid: https://orcid.org/0000-0002-1932-3323
+  - family-names: Commenges
+    given-names: Hadrien
+  year: '2023'
+- type: software
+  title: knitr
+  abstract: '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: xie@yihui.name
+    orcid: https://orcid.org/0000-0003-0645-5666
+  year: '2023'
+- type: software
+  title: rmarkdown
+  abstract: '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: jj@posit.co
+  - family-names: Xie
+    given-names: Yihui
+    email: xie@yihui.name
+    orcid: https://orcid.org/0000-0003-0645-5666
+  - family-names: Dervieux
+    given-names: Christophe
+    email: cderv@posit.co
+    orcid: https://orcid.org/0000-0003-4474-2498
+  - family-names: McPherson
+    given-names: Jonathan
+    email: jonathan@posit.co
+  - family-names: Luraschi
+    given-names: Javier
+  - family-names: Ushey
+    given-names: Kevin
+    email: kevin@posit.co
+  - family-names: Atkins
+    given-names: Aron
+    email: aron@posit.co
+  - family-names: Wickham
+    given-names: Hadley
+    email: hadley@posit.co
+  - family-names: Cheng
+    given-names: Joe
+    email: joe@posit.co
+  - family-names: Chang
+    given-names: Winston
+    email: winston@posit.co
+  - family-names: Iannone
+    given-names: Richard
+    email: rich@posit.co
+    orcid: https://orcid.org/0000-0003-3925-190X
+  year: '2023'
+- type: software
+  title: tinytest
+  abstract: 'tinytest: Lightweight and Feature Complete Unit Testing Framework'
+  notes: Suggests
+  url: https://github.com/markvanderloo/tinytest
+  repository: https://CRAN.R-project.org/package=tinytest
+  authors:
+  - family-names: van der Loo
+    given-names: Mark
+    email: mark.vanderloo@gmail.com
+    orcid: https://orcid.org/0000-0002-9807-4686
+  year: '2023'
+- type: software
+  title: covr
+  abstract: 'covr: Test Coverage for Packages'
+  notes: Suggests
+  url: https://covr.r-lib.org
+  repository: https://CRAN.R-project.org/package=covr
+  authors:
+  - family-names: Hester
+    given-names: Jim
+    email: james.f.hester@gmail.com
+  year: '2023'
diff --git a/codemeta.json b/codemeta.json
new file mode 100644
index 0000000..4a715c6
--- /dev/null
+++ b/codemeta.json
@@ -0,0 +1,308 @@
+{
+  "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
+  "@type": "SoftwareSourceCode",
+  "identifier": "cartography",
+  "description": "Create and integrate maps in your R workflow. This package helps to design cartographic representations such as proportional symbols, choropleth, typology, flows or discontinuities maps. It also offers several features that improve the graphic presentation of maps, for instance, map palettes, layout elements (scale, north arrow, title...), labels or legends. See Giraud and Lambert (2017) <doi:10.1007/978-3-319-57336-6_13>.",
+  "name": "cartography: Thematic Cartography",
+  "codeRepository": "https://github.com/riatelab/cartography/",
+  "issueTracker": "https://github.com/riatelab/cartography/issues/",
+  "license": "https://spdx.org/licenses/GPL-3.0",
+  "version": "3.1.4",
+  "programmingLanguage": {
+    "@type": "ComputerLanguage",
+    "name": "R",
+    "url": "https://r-project.org"
+  },
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+  "provider": {
+    "@id": "https://cran.r-project.org",
+    "@type": "Organization",
+    "name": "Comprehensive R Archive Network (CRAN)",
+    "url": "https://cran.r-project.org"
+  },
+  "author": [
+    {
+      "@type": "Person",
+      "givenName": "Timothée",
+      "familyName": "Giraud",
+      "email": "timothee.giraud@cnrs.fr",
+      "@id": "https://orcid.org/0000-0002-1932-3323"
+    },
+    {
+      "@type": "Person",
+      "givenName": "Nicolas",
+      "familyName": "Lambert",
+      "email": "nicolas.lambert@cnrs.fr"
+    }
+  ],
+  "contributor": [
+    {
+      "@type": "Person",
+      "givenName": "Diego",
+      "familyName": "Hernangómez",
+      "@id": "https://orcid.org/0000-0001-8457-4658"
+    }
+  ],
+  "copyrightHolder": [
+    {
+      "@type": "Person",
+      "givenName": "Ian",
+      "familyName": "Fellows"
+    }
+  ],
+  "maintainer": [
+    {
+      "@type": "Person",
+      "givenName": "Timothée",
+      "familyName": "Giraud",
+      "email": "timothee.giraud@cnrs.fr",
+      "@id": "https://orcid.org/0000-0002-1932-3323"
+    }
+  ],
+  "softwareSuggestions": [
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+      "@type": "SoftwareApplication",
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+      "name": "lwgeom",
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+        "url": "https://cran.r-project.org"
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+      "provider": {
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+      "sameAs": "https://CRAN.R-project.org/package=rmarkdown"
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+    {
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+      "name": "tinytest",
+      "provider": {
+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
+      },
+      "sameAs": "https://CRAN.R-project.org/package=tinytest"
+    },
+    {
+      "@type": "SoftwareApplication",
+      "identifier": "covr",
+      "name": "covr",
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+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
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+      "identifier": "classInt",
+      "name": "classInt",
+      "provider": {
+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
+      },
+      "sameAs": "https://CRAN.R-project.org/package=classInt"
+    },
+    "3": {
+      "@type": "SoftwareApplication",
+      "identifier": "curl",
+      "name": "curl",
+      "provider": {
+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
+      },
+      "sameAs": "https://CRAN.R-project.org/package=curl"
+    },
+    "4": {
+      "@type": "SoftwareApplication",
+      "identifier": "graphics",
+      "name": "graphics"
+    },
+    "5": {
+      "@type": "SoftwareApplication",
+      "identifier": "methods",
+      "name": "methods"
+    },
+    "6": {
+      "@type": "SoftwareApplication",
+      "identifier": "png",
+      "name": "png",
+      "provider": {
+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
+      },
+      "sameAs": "https://CRAN.R-project.org/package=png"
+    },
+    "7": {
+      "@type": "SoftwareApplication",
+      "identifier": "raster",
+      "name": "raster",
+      "provider": {
+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
+      },
+      "sameAs": "https://CRAN.R-project.org/package=raster"
+    },
+    "8": {
+      "@type": "SoftwareApplication",
+      "identifier": "Rcpp",
+      "name": "Rcpp",
+      "provider": {
+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
+      },
+      "sameAs": "https://CRAN.R-project.org/package=Rcpp"
+    },
+    "9": {
+      "@type": "SoftwareApplication",
+      "identifier": "sf",
+      "name": "sf",
+      "provider": {
+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
+      },
+      "sameAs": "https://CRAN.R-project.org/package=sf"
+    },
+    "10": {
+      "@type": "SoftwareApplication",
+      "identifier": "sp",
+      "name": "sp",
+      "provider": {
+        "@id": "https://cran.r-project.org",
+        "@type": "Organization",
+        "name": "Comprehensive R Archive Network (CRAN)",
+        "url": "https://cran.r-project.org"
+      },
+      "sameAs": "https://CRAN.R-project.org/package=sp"
+    },
+    "11": {
+      "@type": "SoftwareApplication",
+      "identifier": "stats",
+      "name": "stats"
+    },
+    "12": {
+      "@type": "SoftwareApplication",
+      "identifier": "utils",
+      "name": "utils"
+    },
+    "13": {
+      "@type": "SoftwareApplication",
+      "identifier": "grDevices",
+      "name": "grDevices"
+    },
+    "SystemRequirements": null
+  },
+  "fileSize": "5688.502KB",
+  "citation": [
+    {
+      "@type": "ScholarlyArticle",
+      "datePublished": "2016",
+      "author": [
+        {
+          "@type": "Person",
+          "givenName": "Timothée",
+          "familyName": "Giraud"
+        },
+        {
+          "@type": "Person",
+          "givenName": "Nicolas",
+          "familyName": "Lambert"
+        }
+      ],
+      "name": "cartography: Create and Integrate Maps in your R Workflow",
+      "identifier": "10.21105/joss.00054",
+      "url": "http://dx.doi.org/10.21105/joss.00054",
+      "@id": "https://doi.org/10.21105/joss.00054",
+      "sameAs": "https://doi.org/10.21105/joss.00054",
+      "isPartOf": {
+        "@type": "PublicationIssue",
+        "issueNumber": "4",
+        "datePublished": "2016",
+        "isPartOf": {
+          "@type": ["PublicationVolume", "Periodical"],
+          "volumeNumber": "1",
+          "name": "JOSS"
+        }
+      }
+    },
+    {
+      "datePublished": "2017",
+      "author": [
+        {
+          "@type": "Person",
+          "givenName": "Timothée",
+          "familyName": "Giraud"
+        },
+        {
+          "@type": "Person",
+          "givenName": "Nicolas",
+          "familyName": "Lambert"
+        }
+      ],
+      "name": "Reproducible Cartography",
+      "identifier": "10.1007/978-3-319-57336-6_13",
+      "pagination": "173-183",
+      "@id": "https://doi.org/10.1007/978-3-319-57336-6_13",
+      "sameAs": "https://doi.org/10.1007/978-3-319-57336-6_13"
+    }
+  ]
+}