R Markdown is a similar feature for the “new team” in LaTex?

Question

Does R Markdown have a similar design for LaTex "newcommand"? I would like things like \varto be \mathrm{Var}in order to avoid unnecessary input in mathematical mode. If not, what are people doing to reduce repetition in sets of equations in markdowns?

Answer 1

Use \newcommand{\var}{\mathrm{Var}}exactly the same as in LaTeX:

---
title: "Untitled"
author: "An Author"
date: "January 15, 2017"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```

\newcommand{\var}{\mathrm{Var}}

## R Markdown

This is an R Markdown document. $\var+2$ Markdown is a simple formatting syntax for 
authoring HTML, PDF, and MS Word documents. For more details on using R Markdown 
see <http://rmarkdown.rstudio.com>.

Please note that in order to properly handle the output you should use $... $.

Answer 2

\DeclareMathOperator , \operatorname:

\newcommand{\Var}{\operatorname{Var}}

$\Var(X)$

( \operatorname , \mathrm)

\newcommand HTML, LaTeX $ $$. , \begin{align*}.

---
title: "Test"
author: "qwr"
date: "January 22, 2019"
output: html_document
---

\newcommand{\Var}{\operatorname{Var}}

$\Var(X)$

$$
\begin{align*}
\Var[Y] &= x \\
&= 3
\end{align*}
$$

Answer 3

, ($$. $$, $. $). .

---
title: Title
author: Author
date: "8/22/2018"
output:
  beamer_presentation:
    includes:
      in_header: preamble.tex
---

preamble.tex ()

\newcommand{\var}{\mathrm{Var}}

inline ($\var $), ($$\var $$)

preamble.tex ..

Answer 4

I use bookdownand bookdownneed to have something that works in concert to output PDF, HTML and DOCX. None of the above solutions worked for my case. Here's the hack I settled on:

preamble.tex

\usepackage{amsthm}
\DeclareMathOperator*{\argmin}{argmin}
\newcommand{\var}{\mathrm{Var}}

YAML Header:

--- 
title: "A Minimal Book Example"
author: "Yihui Xie"
date: "'r Sys.Date()'"
site: bookdown::bookdown_site
output: 
  bookdown::pdf_book:
    includes:
      in_header: preamble.tex
    toc: no
  bookdown::word_document2:
    reference_docx: template.docx
  bookdown::gitbook:
    split_by: none
documentclass: article
bibliography: [book.bib, packages.bib]
biblio-style: apalike
link-citations: yes
---

<!--- For HTML Only --->
'r if (!knitr:::is_latex_output()) '
$\\DeclareMathOperator*{\\argmin}{argmin}$
$\\newcommand{\\var}{\\mathrm{Var}}$
''

<!--- For DOCX Only --->
'r if (!knitr:::is_latex_output() & !knitr:::is_html_output()) '
\\DeclareMathOperator*{\\argmin}{argmin}
\\newcommand{\\var}{\\mathrm{Var}}
''
# Prerequisites

This is a _sample_ book written in **Markdown**.