Convert an R reStructuredText document (Rrst) to R Markdown (Rmd)

rrst_to_rmd.R

#' Converts an R reStructuredText document (Rrst) to R Markdown (Rmd)
#'
#' @param input character string with the path of the file to convert
#' @param output optional character string with the path for the output file
#' @param out_dir optional character string with the output directory. Not used
#'   if \code{output} is supplied.
#' @param output_file logical whether to return the output to a file or not.
#' If \code{FALSE}, then \code{output} and \code{out_dir} are ignored.
#'
#' @importFrom readr read_file write_file
#' @importFrom tools file_path_sans_ext

rrst_to_rmd <- function(input, output, out_dir, output_file = TRUE) {
    library(readr)
    library(tools)

    if (!file.exists(input))
        stop(sprintf('Unable to find %s', input))

    # Find basic file name and file path
    input_name <- file_path_sans_ext(basename(input))

    # Read file into R
    txt <- read_file(input)

    # Function to replace rst blocks
    block_replace <- function(txt, block_open, replace_open, replace_close) {
        txt <- gsub(sprintf('(%s)(\\n\\n)', block_open), '\\1', txt, perl = TRUE)
        txt <- gsub(sprintf('(%s)(\\n\\n)', block_open), '\\1', txt, perl = TRUE)
        txt <- gsub(sprintf('(%s)(\\s+)', block_open), '\\1', txt)
        txt <- gsub(sprintf('%s.+?\\K(\\n{1} +)', block_open), 'PLACEHOLDER', txt,
                    perl = TRUE)
        txt <- gsub(sprintf('%s.*\\K\\n\\n', block_open), replace_close, txt, perl = TRUE)
        txt <- gsub(sprintf('.. %s', block_open), replace_open, txt, perl = TRUE)
        txt <- gsub('PLACEHOLDER', '\n        ', txt, perl = TRUE)
        return(txt)
    }

    #### Conversions -----------------------------------------------------------
    # h1
    txt_edit <- gsub('\\n~~~~*\\n', '\n======\n', txt)
    # h2
    txt_edit <- gsub('\\n\\+\\+\\+\\+*\\n', '\n------\n', txt_edit)
    # h3
    txt_edit <- gsub('\\n\\!\\!\\!\\!*\\n', '\\!\\!\\!\\!\\!\\!\\!\\!\n',
                     txt_edit)
    txt_edit <- gsub('(\\n\\n){1}(.+?)(\\!\\!\\!\\!\\!\\!\\!\\!)',
                     '\n\n### \\2', txt_edit, perl = TRUE)

    # hyperlinks
    txt_edit <- gsub('``', 'INLINEPLACEHOLDER', txt_edit)
    txt_edit <- gsub('(>)(`){1}(_)', ')', txt_edit, perl = TRUE)
    txt_edit <- gsub('(`){1}(.*?)(<)', '[\\2](', txt_edit, perl = TRUE)

    # inline math
    txt_edit <- gsub('(?<!`)(?<=(?!``).)`(?!`)', '$', txt_edit, perl = TRUE)
    txt_edit <- gsub(":math:", '', txt_edit)

    # inline code chunks
    txt_edit <- gsub('INLINEPLACEHOLDER', '`', txt_edit)

    # display code chunks
    txt_edit <- gsub('\\n\\.\\. \\{', '\n```{', txt_edit)
    txt_edit <- gsub('\\n\\.\\. \\.\\.', '\n```', txt_edit)

    # math block
    txt_edit <- block_replace(txt_edit, block_open = 'math::',
                              replace_open = '\n$$\n    ',
                              replace_close = '\n$$\n\n')

    # static source block
    txt_edit <- block_replace(txt_edit, block_open = 'sourcecode:: r',
                              replace_open = '\n```{r eval=FALSE}\n',
                              replace_close = '\n```\n\n')

    # image
    txt_edit <- block_replace(txt_edit, block_open = 'image::',
                              replace_open = '[](',
                              replace_close = ')\n\n')

    # Cleanup
    txt_edit <- gsub('\\n\\n\\n', '\n\n', txt_edit)
    txt_edit <- gsub('(\\s)(\\])', '\\2', txt_edit, perl = TRUE)

    # Return output ------------------------------------------------------------
    if (isTRUE(output_file)) {
        if (missing(output)) {
            if (missing(out_dir))
                input_path <- dirname(input)
            else input_path <- out_dir
            output <- paste0(input_path, '/', input_name, '.Rmd')
        }
        write_file(txt_edit, path = output)
    }
    else
        return(txt_edit)
}

zelig_converter.R

# Implements rrst_to_rmd.R in a specific context

library(devtools)
library(tools)
library(readr)
library(whisker)
library(rmarkdown)

converterfun_url <- 'https://gist.githubusercontent.com/christophergandrud/d6400a99b37bf702bcad81af03437da6/raw/0cfca6ccdc4b05cd0ade36c3de6c479b69be79e8/rrst_to_rmd.R'
source(converterfun_url)

doc_template <- '~/Desktop/doc_rmd/header_template.txt'
out_path <- '~/Desktop/doc_rmd/out'

setwd('~/Desktop/docsource/')
files <-list.files()
rrst_files <- files[grepl('.Rrst$', files)]
rrst_files <- rrst_files[!(rrst_files %in% c('features.Rrst', 'index.Rrst',
                                             'zelig-lsmixed.Rrst',
                                             'zelig-relogit.Rrst',
                                             'zeligei-eiml.Rrst',
                                         #    'zeligei-eirxc.Rrst',
                                             'zeliggam_logitgam.Rrst'))]

# rrst to rmd
for (i in rrst_files) {
    message(i)
    input <- i

    base_rmd <- rrst_to_rmd(input = input, output_file = FALSE)
    base_rmd <- gsub('^...*?======', '', base_rmd)
    base_rmd <- gsub('\\$getcoef\\(\\)', '$get_coef()', base_rmd)
    base_rmd <- gsub('\\$getvcov\\(\\)', '$get_vcov()', base_rmd)
    base_rmd <- gsub('\\$getpredict\\(\\)', '$get_predict()', base_rmd)

    input_name <- file_path_sans_ext(basename(input))

    header <- whisker.render(read_file(doc_template),
                             data = list(page_name = input_name,
                                         page_name2 = sprintf('{%s}', input_name)))
    input_name <- gsub('-', '_', input_name)

    cat(header, base_rmd, file = sprintf('%s/%s.Rmd', out_path, input_name))
}

# Can compile to html
rmd_files <- gsub('\\.Rrst', '.Rmd', rrst_files)
rmd_files <- gsub('-', '_', rmd_files)
setwd(out_path)
for (i in rmd_files)
    render(i)

Note this is pretty limited in that it currently only converts:

• headers up to level 3

• hyperlinks

• inline and display code chunks (including non-evaluated sourcecode:: r

• inline and display equations

A lot of the other syntax is shared between RST and R Markdown.