The aim of the filter is to replace ampersands in in-sentence citations generated by
pandoc-citeproc relies on the Citation Style Language (CSL) to specify citation styles. A drawback of this standard is, that it does not specify citations that are part of the sentence, rather than in parentheses. Hence,
pandoc-citeproc uses the same style for both citation forms. Some author-year citation styles, however, demand slightly different styles for in-sentence and in-parentheses citations. For example, according to APA style author names should be joined by
& in parentheses but by
and in a sentence. The ampersand replacement filter addresses this problem, by replacing ampersands in in-sentence citations with
and or its equivalent in other languages. This, of course, necessitates that the filter is applied after
pandoc-citeproc. To do so, it is necessary to disable the default application of
pandoc-citeproc, because it is always applied last, by adding the following to the documents YAML front matter:
To manually apply
pandoc-citeproc and subsequently the ampersand replacement filter add the
pandoc arguments to the output format of your R Markdown document as
pandoc_args. Each filter returns a vector of command line arguments; they take previous arguments as
args and add to them. Hence, the calls to add filters can be nested:
#>  "--filter" #>  "/Applications/RStudio.app/Contents/MacOS/pandoc/pandoc-citeproc"
#>  "--filter" #>  "/Applications/RStudio.app/Contents/MacOS/pandoc/pandoc-citeproc" #>  "--lua-filter" #>  "/private/var/folders/nv/mz4ffsbn045101ngdd_mx0th0000gn/T/Rtmpp9G8mG/Rinsta4a16c970fe/rmdfiltr/replace_ampersands.lua"
When adding the filters to
pandoc_args the R code needs to be preceded by
!expr to declare it as to-be-interpreted expression.
By default, it is assumed that the document language is English and
& is replaced by
and. Other languages can be specified with the
lang, which requires a language and region tag. For example, to replace
& by the German
und add the following to the document YAML front matter: