## rmarkdown: Alter Action Depending on Document

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,
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
}
\\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.

I am Literacy PhD student with a bent for the quantitative and a passion for R.
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### 6 Responses to rmarkdown: Alter Action Depending on Document

• tylerrinker says:

Yes but the title is highly unlikely to lead a searcher there unless one had latin character specific problems.

• Jo says:

That’s exactly right. I have been looking for a way to do this and was unable to find anything until I saw a tweet about this post.

1. Great solution for xtable dilemmas.