add CITATION.cff

.Rbuildignore

@@ -12,3 +12,4 @@ autom4te.cache
 ^docs$
 ^pkgdown$
 ^\.github$
+^CITATION\.cff$

CITATION.cff

@@ -0,0 +1,46 @@
+cff-version: 1.2.0
+title: 'apcf: Adapted Pair Correlation Function'
+message: >-
+  If you use the apcf package, please cite both the article
+  from preferred-citation and the software itself.
+type: software
+authors:
+  - family-names: Nuske
+    given-names: Robert
+    orcid: 'https://orcid.org/0000-0001-9773-2061'
+identifiers:
+  - type: doi
+    value: 10.5281/zenodo.2535612
+repository-code: 'https://github.com/rnuske/apcf'
+url: 'https://rnuske.github.io/apcf/'
+repository: 'https://CRAN.R-project.org/package=apcf'
+abstract: >-
+  The adapted pair correlation function transfers the
+  concept of the pair correlation function from point
+  patterns to patterns of objects of finite size and
+  irregular shape (e.g. lakes within a country). The pair
+  correlation function describes the spatial distribution of
+  objects, e.g. random, aggregated or regularly spaced. This
+  is a reimplementation of the method suggested by Nuske et
+  al. (2009) using the library 'GEOS'.
+license: GPL-3.0-or-later
+version: 0.3.0
+date-released: '2022-11-11'
+preferred-citation:
+  type: article
+  title: >-
+    Adapting the pair-correlation function for analysing the spatial
+    distribution of canopy gaps
+  authors:
+    - family-names: Nuske
+      given-names: Robert S.
+    - family-names: Sprauer
+      given-names: Susanne
+    - family-names: Saborowski
+      given-names: Joachim
+  journal: Forest Ecology and Management
+  volume: '259'
+  issue: '1'
+  year: '2009'
+  doi: 10.1016/j.foreco.2009.09.050
+  start: 107-116