Converts R markdown code to ioslides html presentations

Creates accessible html ioslides presentations using R markdown's ioslides_presentation argument to render. Zip archives of the html files may be created.

Usage

rmd2ioslides(
  x,
  zip = if (length(x) == 1 & !add) FALSE else TRUE,
  pdf = FALSE,
  zip_pdf = zip,
  pdf_args = list(),
  add = FALSE,
  quiet = TRUE,
  rm_html = FALSE,
  rm_pdf = FALSE,
  inc_rmd = FALSE,
  params = NULL,
  ...
)

Arguments

x

A character vector containing the names (no extension) of the .Rmd files to convert if they are in the current working directory, or paths to the files, either absolute or relative to the current working directory, e.g., DIRECTORY/file1. The .html files are created in the same directory as their respective .Rmd file. If x is missing then an html file is created from each of the .Rmd files in the current working directory.

zip

A logical scalar or character vector indicating whether html files should be put into a zip archive. If zip = FALSE then no zip archive is created. Otherwise, an archive is created in each unique directory involved in x. If zip = TRUE then any archive created has the name accessr_ioslides.zip. If zip is a character vector of zip file names (no extension) then these names are used to name the zip archives. The names are recycled to the length of the number of unique directories, if necessary.

pdf

A logical scalar. If pdf = TRUE then each html file is printed to a PDF file using chrome_print. Google Chrome (or an alternative browser specified in pdf_args by the browser argument to chrome_print must be installed prior to use of this option. An error message like Error in servr::random_port(NULL) : Cannot find an available TCP port means that the random_port function in the servr package could not find an internet connection that Chrome considers secure. Perhaps you are using a coffee shop's wifi.

zip_pdf

As zip, but relates to the creation of zip archives for any PDF files created. If zip_pdf = TRUE then each archive is named accessr_ioslides_pdf.zip.

pdf_args

A list of arguments passed to chrome_print. input cannot be passed because it is set inside rmd2html.

add

A logical scalar that determines what happens if the output zip file already exists. If add = TRUE then files are added to the zip file and if add = FALSE then the zip file is deleted and will only contain newly-created files.

quiet

Argument of the same name passed to render to determine what is printed during rendering from knitr.

rm_html

A logical scalar. If rm_html = TRUE and a zip archive of html files is produced then the individual html files are deleted. Otherwise, they are not deleted.

rm_pdf

A logical scalar. If rm_pdf = TRUE and a zip archive of pdf files is produced then the individual pdf files are deleted. Otherwise, they are not deleted.

inc_rmd

A logical scalar. If inc_rmd = TRUE then the source Rmd files are included in the zip file created. Otherwise, they are not included.

params

A list of named parameters to pass as the argument params to render.

...

Additional arguments passed to ioslides_presentation. Pass (the default) slide_level = 1 if you want a level one header # to create a new non-segue slide.

If css = "black" is passed then accessr's css file black.css is used, which results in black text being used in the slides.

This function is not vectorised with respect to arguments in ....

Value

In addition to creating the html files, and perhaps zip files, a list containing the following (character vector) components is returned invisibly:

files: (absolute) paths and file names of the files added to a zip file.
zips: (relative) paths and names of all the zip files.

Details

Information such as title, author, lang etc in the YAML header in the Rmd file are used but output is ignored.

The simplest setup is to have the .Rmd files in the current working directory, in which case rmd2ioslides() will create ioslides presentations from all these Rmd files, but the .Rmd files may be in different directories.

The render function, with the argument output_file = ioslides_presentation creates the ioslides html files.

The function ioslides_presentation has an argument slide_level that sets the header level used as a slide separator. The Lua filter ioslides_presentation.lua in the rmarkdown package uses any content between headers of level slide_level to create a segue slide, which has a grey background and is intended only to contain a section heading.

In particular, under the default, slide_level = 2, content between a level one header # and the next level two header ## is formatted as a separate grey segue slide. If we do not want segue slides then we must avoid using level one headers. However, for reasons of document accessibility, we may want to use level one headers to separate slides. For example, if we wish to create an ioslides presentation and a Word document from the same source Rmd file then the Word document will only meet fully accessibility requirements if the headings in the document start at level one.

In rmarkdown version 2.26, passing slide_level = 1 to ioslides_presentation does not force a new non-segue slide when a level one header # is used: it places all content between # and the next ## on a grey segue slide and the behaviour content of the resulting slides is not as intended. Passing slide_level = 1 to rmd2ioslides() replaces rmarkdown's Lua filter ioslides_presentation.lua with one that has been modified, so that passing slide_level = 1 will start a new non-segue slide. A modified default.css css file is also used that adjusts the font sizes for the header levels accordingly, so that the level one header has a larger font than the level two header. For values of slide_level greater than or equal to 2, ioslides_presentation will behave as usual.

If slide_level is not supplied then slide_level = 1 is used.

Examples

# Create an ioslides presentation from example.Rmd
got_hux <- requireNamespace("huxtable", quietly = TRUE)
got_flex <- requireNamespace("flextable", quietly = TRUE)
got_pandoc <- rmarkdown::pandoc_available("1.14")
got_all <- got_hux && got_flex && got_pandoc
# This example needs packages huxtable and flextable
if (got_all) {
  ex_file <- system.file(package = "accessr", "examples", "example.Rmd")
  file.copy(ex_file, tdir <- tempdir(check = TRUE), overwrite = TRUE)
  ex_file <- list.files(tdir, pattern = "example.Rmd", full.names = TRUE)
  ex_file <- sub(".Rmd", "", ex_file)
  rmd2ioslides(ex_file)
}