r - Rmarkdown 文档的字体

Question

这是一个最小的工作示例。

---
date : 2018-May-26
output:
    pdf_document
title: "Testing Rmarkdown"
---

```{r,comment = NA}

Gender <- gl(2,1000,labels = c("Men","Women"))
SmokerM <- sample(c("Y","N"),1000,replace = T , prob = c(.3,.7))
SmokerW <- sample(c("Y","N"),1000,replace = T , prob = c(.5,.5))
Smoker <- c(SmokerM,SmokerW)

mydata  <- data.frame(Gender,Smoker)
table(mydata$Gender,mydata$Smoker)

```

This is a text in the body of the document.What font is this ? What is
font for the output of table ? How can we change these 2 fonts ? What 
other categories of items are there in an Rmarkdown which have different
fonts ?       

我的查询如下: Rmarkdown 文档的默认字体是什么以及如何更改它们？

在研究这个时，我遇到了这个页面:

[Pandoc 变量][1] http://pandoc.org/MANUAL.html#variables-for-latex

是否有 4 种字体(mainfont/sansfont/monofont/mathfont)用于描述 Rmarkdown 中的 4 类输出？它们的默认值是什么，我该如何更改它们？

Answer 1

创建 PDF 文件时使用 LaTeX。 LaTeX 中使用的默认字体是 Computer Modern。有多种方法可以更改 LaTeX 中使用的字体，但是如果不了解 LaTeX，所需的名称通常不直观。一个更简单的解决方案是使用 mainfont等连同xelatex或 lualatex作为发动机。您可以在 yml 的顶层定义这些选项。标题使用平台的标准字体名称。这里使用 Liberation Serif 作为主要字体的示例文档:

---
date : 2018-May-26
output:
    pdf_document:
        latex_engine: xelatex
mainfont: LiberationSerif
sansfont: LiberationSans
monofont: LiberationMono
title: "Testing Rmarkdown"
---

```{r,comment = NA}

Gender <- gl(2,1000,labels = c("Men","Women"))
SmokerM <- sample(c("Y","N"),1000,replace = T , prob = c(.3,.7))
SmokerW <- sample(c("Y","N"),1000,replace = T , prob = c(.5,.5))
Smoker <- c(SmokerM,SmokerW)

mydata  <- data.frame(Gender,Smoker)
table(mydata$Gender,mydata$Smoker)
knitr::kable(table(mydata$Gender,mydata$Smoker))
```

This is a text in the body of the document.What font is this ? What is
font for the output of table ? How can we change these 2 fonts ? What 
other categories of items are there in an Rmarkdown which have different
fonts ?   

第一个表使用mono字体，即Liberation Mono，因为它是正常的R输出。第二个表再次使用主字体。见 documentation更多细节。