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custom labels and counters in r-markdown

Is it possible to create an intext custom counter in r-markdown. For instance, say I have the following text

Einstein was a clever man [Fact 1]. Einstein worked for Princeton University [Fact 2]. Anyone who is employed by Princeton University is clever.

My ideal outcome is to define a counter for facts, with a specific formatting (e.g. bold and red in a bracket). So any time I call the counter it would print the counter label with the new number. Something like

Einstein was a clever man factCounter. Einstein worked for Princeton University factCounter. Anyone who is employed by Princeton University is clever.

Solution

  • A pandoc Lua filter would do the job:

    local utils = require 'pandoc.utils'
local fact_counter = 0

function Code (code)
  if utils.stringify(code) == 'factCounter' then
    fact_counter = fact_counter + 1
    return pandoc.Str(string.format('[Fact %s]', fact_counter))
  end
end

    Just add --lua-filters=FILE-CONTAINING-ABOVE-CODE.lua to your pandoc_args knitr options. All occurences of `factCounter` in your text will be replaced by an actual fact count.