How to convert R Markdown to HTML? I.e., What does "Knit HTML" do in Rstudio 0.96?

Question

What commands are run when pressing "Knit HTML" on an R Markdown file in Rstudio 0.96?

My motivation is that I might want to run the same command when I'm in another text editing environment or I might want to combine the command in a larger makefile.

Answer 1

Basic Script

So now that the R markdown package has been released, here is some code to replicate the features of Knit to Html.

require(knitr) # required for knitting from rmd to md
require(markdown) # required for md to html 
knit('test.rmd', 'test.md') # creates md file
markdownToHTML('test.md', 'test.html') # creates html file
browseURL(paste('file://', file.path(getwd(),'test.html'), sep='')) # open file in browser 

where test.rmd is the name of your R markdown file. Note that I'm not 100% confident about the browseURL line (hence my question here about opening files in a web browser).

markdownToHTML Options

The good thing about markdownToHTML is that there are heaps of options in how the HTML is created (see ?markdownHTMLOptions). So for example, if you want just a code fragment without all the header information, you could write:

markdownToHTML('test.md', 'test.html', options='fragment_only')

or if you don't like hard wrapping (i.e., inserting line breaks when there are single manual line breaks in the markdown source), you can omit the 'hard_wrap' option.

# The default options are 'hard_wrap', 'use_xhtml', 
#      'smartypants', and 'base64_images'.
markdownToHTML('test.md', 'test.html', 
       options=c('use_xhtml', 'base64_images'))

Makefile

This could also all be added to a makefile perhaps using Rscript -e (e.g., something like this). Here's a basic example makefile I put together, where test indicates that the rmd file is called test.rmd.

RMDFILE=test

html :
    Rscript -e "require(knitr); require(markdown); knit('$(RMDFILE).rmd', '$(RMDFILE).md'); markdownToHTML('$(RMDFILE).md', '$(RMDFILE).html', options=c('use_xhtml', 'base64_images')); browseURL(paste('file://', file.path(getwd(),'$(RMDFILE).html'), sep=''))"

The makefile uses my preferred markdown options: i.e., options=c('use_xhtml', 'base64_images')