如何使用单位包与rmarkdown的pdf文件

Question

我在rmarkdown文档中使用单位包进行pdf输出。 但是，这些单元既不能用作内联代码，也不能用作代码块。 是否可以使用rmarkdown的单位？

RSt中的rmarkdown文档的MWE：

---
title: "Units in R Markdown"
output: pdf_document
---

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

```{r define units, include=FALSE}
len <- set_units(5, mm)
wid <- set_units(10, mm)
```


In-line code: The area of the rectangle is `r len * wid`.

```{r echo = FALSE}

paste("The area of the rectangle is ", len * wid)

```

I'm expecting to see: The area of the rectangle is `r len * wid`mm^2

rmarkdown pdf文件的图片：

Answer 1

普通R会话中的print(len * wid)将产生相同的结果。 单位是特殊对象，需要特殊方法才能转换为字符串。 尝试这个：

---
title: "Units in R Markdown"
date: "May 12, 2018"
output: pdf_document
---

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

```{r define units, include=FALSE}
len <- set_units(5, mm)
wid <- set_units(10, mm)
paste("The area of the rectangle is ", format(len * wid))
```


In-line code: The area of the rectangle is `r format(len * wid)`.

```{r echo = FALSE}

paste("The area of the rectangle is ", format(len * wid))

```

I'm expecting to see: The area of the rectangle is `r format(len * wid)`