R/slides2notes.R

In webbedfeet/coursedown: Creating course materials using R Markdown

#' Translate a xaringan slide into a bookdown chapter
#'
#' @param infile Relative path name to the slide RMarkdown fille
#' @param outdir Relative path where bookdown chapter will reside
#' @param outfile (default = `basename(infile)`) name of output file (without full path)
#'
#' @return A RMarkdown file formatted as a  bookdown chapter
#' @export
#'
#' @examples
#' # slide2note('slides/ggplot.Rmd')
slide2note <- function(infile, outdir = 'notes', outfile = basename(infile)){
  requireNamespace("tidyverse")
  outfile <- file.path(outdir, outfile)
  file_contents <- readLines(infile)
  ind <- which(purrr::map_lgl(file_contents, str_detect,'---'))
  title <- rmarkdown:::parse_yaml_front_matter(file_contents)$title
  title <- paste('#',title)
  bl <- file_contents[-(1:ind[2])] # remove frontmatter
  bl <- bl %>%
    `[`(!str_detect(., 'class')) %>%
    `[`(!str_detect(., '---')) %>%
    `[`(!str_detect(.,'layout')) %>%
    `[`(!str_detect(., 'span')) %>%
    str_replace('^#','##') %>%
    c(c(title,''),.)
  writeLines(bl, con=file(outfile))
  yml <- yaml::read_yaml(file.path(outdir,'_bookdown.yml'))
  yml$rmd_files$html <- unique(c(yml$rmd_files$html, basename(outfile)))
  yml$rmd_files$latex <- unique(c(yml$rmd_files$latex, basename(outfile)))
  yaml::write_yaml(yml, file.path(outdir,'_bookdown.yml'))
}