Skip to contents

High Performance CommonMark and Github Markdown Rendering in R

CRAN_Status_Badge CRAN RStudio mirror downloads

The CommonMark specification defines a rationalized version of markdown syntax. This package uses the ‘cmark’ reference implementation for converting markdown text into various formats including html, latex and groff man. In addition it exposes the markdown parse tree in xml format. The latest version of this package also adds support for Github extensions including tables, autolinks and strikethrough text.

Basic Markdown

md <- "## Test
An *example* text for the `commonmark` package."

# Convert to Latex

An \emph{example} text for the \texttt{commonmark} package.
# Convert to HTML
<p>An <em>example</em> text for the <code>commonmark</code> package.</p>
# Convert to 'groff' man 
An \f[I]example\f[] text for the \f[C]commonmark\f[] package.
# Convert back to (normalized) markdown
## Test

An *example* text for the `commonmark` package.
# The markdown parse tree
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE document SYSTEM "CommonMark.dtd">
<document xmlns="">
  <heading level="2">
    <text>An </text>
    <text> text for the </text>
    <text> package.</text>

Github Extensions

Commonmark includes several ‘extensions’ to enable features which are not (yet) part of the official specification. The current version of the commonmark R package offers 4 such extensions:

  • table support rendering of tables
  • strikethough via ~sometext~ syntax
  • autolink automatically turn URLs into hyperlinks
  • tagfilter blacklist html tags: title textarea style xmp iframe noembed noframes script plaintext.
  • tasklist turns certain list items into checkboxes

These extensions were added by Github to support GitHub Flavored Markdown.

table <- '
aaa | bbb | ccc | ddd | eee
:-- | --- | :-: | --- | --:
fff | ggg | hhh | iii | jjj'

cat(markdown_latex(table, extensions = TRUE))
aaa & bbb & ccc & ddd & eee \\
fff & ggg & hhh & iii & jjj \\
cat(markdown_html(table, extensions = TRUE))
<th align="left">aaa</th>
<th align="center">ccc</th>
<th align="right">eee</th>
<td align="left">fff</td>
<td align="center">hhh</td>
<td align="right">jjj</td>