ifelse 操作取决于 rmarkdown 中的文档类型 [英] ifelse action depending on document type in rmarkdown

问题描述

使用 rmarkdown 准备报告时:http://rmarkdown.rstudio.com/ 人们可能希望文档根据文档类型进行不同的呈现.例如，如果呈现的文档是一个 html 文件，我可能想要嵌入一个 youtube 视频，而如果它是 pdf 或 MS Word，我想要的是超链接的 URL.

When preparing reports using rmarkdown: http://rmarkdown.rstudio.com/ one may want the document to render differently depending upon the document type. For instance I may want to embed a youtube video if the document being rendered is an html file where as if it's pdf or MS Word I would want the hyper-linked URL instead.

有没有办法告诉 rmarkdown 像这样:

Is there a way to tell rmarkdown something like this:

if (html) {
    <iframe width="640" height="390" src="https://www.youtube.com/embed/FnblmZdTbYs?    feature=player_detailpage" frameborder="0" allowfullscreen></iframe>
} else {
    https://www.youtube.com/watch?v=ekBJgsfKnlw
}

代码

devtools::install_github("rstudio/rmarkdown")
library(rmarkdown)
render("foo.Rmd", "all")

foo.Rmd

---
title: "For Fun"
date: "`r format(Sys.time(), '%d %B, %Y')`"
output:
  html_document:
    toc: true
    theme: journal
    number_sections: true
  pdf_document:
    toc: true
    number_sections: true
  word_document:
    fig_width: 5
    fig_height: 5
    fig_caption: true
---

## Good times

<iframe width="640" height="390" src="https://www.youtube.com/embed/FnblmZdTbYs?feature=player_detailpage" frameborder="0" allowfullscreen></iframe>

推荐答案

是的，您可以通过 knitr::opts_knit$get("rmarkdown.pandoc.to") 访问输出格式.这将返回一个具有目标输出格式的字符串.举个例子:

Yes, you can access the output format via knitr::opts_knit$get("rmarkdown.pandoc.to"). This will return a string with the target output format. Here's an example:

---
title: "Untitled"
output: html_document
---

```{r}
library(knitr)
opts_knit$get("rmarkdown.pandoc.to")
```

这为 html_document 返回html"，为 word_document 返回docx"，为 pdf_document 返回latex".因此，要回答您的问题，您可以执行以下操作:

This returns "html" for html_document, "docx" for word_document, and "latex" for pdf_document. So to answer your question you can do something like:

html <- knitr::opts_knit$get("rmarkdown.pandoc.to") == "html"

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