How to include LaTeX package in R Markdown?

Question

I am writing a report with Rmd in RStudio via knitr package.

I want to write a indicator variable symbol in the report, like How do you get \mathbb{1} to work (characteristic function of a set)?.

The line \usepackage{bbm} should be included according to the answer.

I tried first

$$
\usepackage{bbm}
y_{ij} = b_{ij} + \beta_{0} + \beta_{1}
$$

But the program cannot interpret \usepackage{bbm}.

Answer 1

I think this is the easiest option!

---
title: "Title"
author: "Me"
header-includes:
   - \usepackage{bbm}
output:
    pdf_document
---

(Edited to have three, instead of four, hyphens to open and close the YAML front-matter)

Answer 2

As per this page on the R Markdown website, you can add whatever you want to the preamble via the in-header option in the YAML header; e.g.,

----
title: "Titre"
date: Fecha
output:
    pdf_document:
        includes:
            in_header: mystyles.sty
----

In mystyles.sty, located in the same directory as the .Rmd, you could have a whole list of additional things to add to the preamble of document, e.g.:

\usepackage{bbm}
\usepackage{threeparttable}
\usepackage{booktabs}
\usepackage{expex}

Etc. The contents of mystyles.sty are then pasted into the LaTeX preamble; check out the default LaTeX template used here to see where precisely in the preamble they are included.

As a minimal example I tested an Rmd document with the header from above including the .sty from above and having the following in the body of the document:

$$ y_{ij} = b_{ij} + \beta_{0} + \beta_{1} $$

Test test $\mathbb{1}$ test.

Answer 3

As of rmarkdown version 1.4 it has been possible to use the extra_dependencies parameter to list a character vector of LaTeX packages. This is useful if you need to load multiple packages:

---
title: "Untitled"
output: 
  pdf_document:
    extra_dependencies: ["bbm", "threeparttable"]
---

If you need to specify options when loading the package, you can add a second-level to the list and provide the options as a list:

output: 
  pdf_document:
    extra_dependencies:
      hyperref: ["unicode=true", "breaklinks=true"]
      lmodern: null