(This article was originally published at TRinker's R Blog, and syndicated at StatsBlogs.)
Can I see a show of hands for those who love rmarkdown? Yeah me too. One nifty feature is the ability to specify various document prettifications in the YAML of a .Rmd document and then use:
rmarkdown::render("foo.Rmd", "all")
The Problem
Have you ever said, “I wish I could do X for document type A and Y for document type B”? I have, as seen in this SO question from late August. But my plea went unanswered until today…
The Solution
Baptiste Auguie answered a similar question on SO. The key to Baptiste’s answer is this:
```{r, echo=FALSE}
out_type <- knitr::opts_knit$get("rmarkdown.pandoc.to")
```
This basically says “Document. Figure out what type you are”. You can then feed this information to if () {} else {}, switch(), etc. and act differently, depending on the type of document being rendered. If Baptiste is correct the options and flexibility are endless.
I decided to put Baptiste’s answer to the test on more complex scenarios. Here it is as GitHub repo that you can fork and/or download and try at home.
Simple Example
To get a sense of how this is working let’s start with a simple example. I will assume some familiarity with rmarkdown and the YAML system. Here we will grab the info from knitr::opts_knit$get("rmarkdown.pandoc.to") and feed it to a switch() statement and act differently for a latex, docx, and html document.
---
title: "For Fun"
date: "`r format(Sys.time(), '%d %B, %Y')`"
output:
html_document:
toc: true
theme: journal
number_sections: true
pdf_document:
toc: true
number_sections: true
word_document:
fig_width: 5
fig_height: 5
fig_caption: true
---
```{r, echo=FALSE}
out_type <- knitr::opts_knit$get("rmarkdown.pandoc.to")
```
## Out Type
```{r, echo=FALSE}
print(out_type)
```
## Good times
```{r, results='asis', echo=FALSE}
switch(out_type,
html = "I'm HTML",
docx = "I'm MS Word",
latex = "I'm LaTeX"
)
```
The result for each document type is using rmarkdown::render("simple.Rmd", "all"):
HTML Document
LaTeX Document
docx Document
Extended Example
That’s great but my boss ain’t gonna be impressed with printing different statements. Let’s put this to the test. I want to embed a video into the HTML and PDF (LaTeX) or just put a url for an MS Word (docx) document. By the way if someone has a way to programmaticly embed the video in the docx file please share.
For this setup we can use a standard iframe for HTML and the media9 package for the LaTeX version to add a YouTube video. Note that not all PDF viewers can render the video (Adobe worked for me PDF XChange Viewer did not). We also have to add a small tweak to include the media9 package in a .sty (quasi preamble) using this line in the YAML:
includes:
in_header: preambleish.sty
And then create a separate .sty file that includes LaTeX package calls and other typical actions done in a preamble.
---
title: "For Fun"
date: "`r format(Sys.time(), '%d %B, %Y')`"
output:
html_document:
toc: true
theme: journal
number_sections: true
pdf_document:
toc: true
number_sections: true
includes:
in_header: preambleish.sty
word_document:
fig_width: 5
fig_height: 5
fig_caption: true
---
```{r, echo=FALSE}
out_type <- knitr::opts_knit$get("rmarkdown.pandoc.to")
```
## Out Type
```{r, echo=FALSE}
print(out_type)
```
## Good times
```{r, results='asis', echo=FALSE}
switch(out_type,
html = {cat('<a href="https://www.youtube.com/embed/FnblmZdTbYs?feature=player_detailpage">https://www.youtube.com/embed/FnblmZdTbYs?feature=player_detailpage</a>')},
docx = cat("https://www.youtube.com/watch?v=ekBJgsfKnlw"),
latex = cat("\\begin{figure}[!ht]
\\centering
\\includemedia[
width=0.6\\linewidth,height=0.45\\linewidth,
activate=pageopen,
flashvars={
modestbranding=1 % no YT logo in control bar
&autohide=1 % controlbar autohide
&showinfo=0 % no title and other info before start
}
]{}{http://www.youtube.com/v/ekBJgsfKnlw?rel=0} % Flash file
\\caption{Important Video.}
\\end{figure}" )
)
```
The result for each document type is using rmarkdown::render("extended.Rmd", "all"):
HTML Document
LaTeX Document
docx Document
I hope this post extends flexibility and speeds up workflow for folks. Thanks to @Baptiste for a terrific solution.
Please comment on the article here: TRinker's R Blog
