我该如何在Rmd中使用Latex的\newcommand命令？

Question

我希望你能帮我完成如下工作。

---
title: "Untitled"
author: "SQC"
date: "21 September 2018"
output: html_document
---

\newcommand{\short}{AreallylongwordIhavetotypefrequently}

# My Test
I would like to write \short which does not work, $\short$ however is close... 
Snippets do not work in Rmd plain text (= Rstudio's "Shift", see link below).

但是我找不到解决方案。如果有什么好的方法就太棒了！以下链接很有帮助，但都没有提供解决方案：pandoc文档、\newcommand在Rmd公式中的应用和RStudio代码片段。

- Christoph

Answer 1

如何使用R语言替代呢：

---
title: "Untitled"
author: "SQC"
date: "21 September 2018"
output: html_document
---

```{r, include = FALSE}
short <- "AreallylongwordIhavetotypefrequently"
```

# My Test
I would like to write `r short` instead ...

- Ralf Stubner

---

太棒了 - 如此简单！！ - Christoph

也许你知道这个问题的答案 在这里？;-) - Christoph

@Christoph 抱歉，我不知道如何解决这个问题。 - Ralf Stubner

Answer 2

如果你仍需要在Rmarkdown中使用LaTeX定义\newcommand，你可以这样做：

Some text with the following equation:

\begin{equation} \newcommand{\matr}[1]{\mathbf{#1}}
\matr{Y} =
\begin{pmatrix}
\matr{y_1} \\
\matr{y_2} \\
\end{pmatrix}
\end{equation}

```{r}
y1 + y2
```

请注意，使用此功能需要加载bm包，例如在YAML头中使用以下内容：

---
title: "My R Report" 
author: "Me" 
date: "2020-01-31" 
header-includes: 
  - \usepackage{bm} 
output: 
  pdf_document: 
    toc: true 
    number_sections: true
---

- This_is_it