在Knitr中的行之间拆分R块头 [英] Split r chunk header across lines in knitr

问题描述

当我在R块标题中插入长标题之类的内容时，能够将标题分成多行会很好.

When I'm inserting long captions and the like in my R chunk header, it'd be nice to be able to split the header across multiple lines.

有没有简单的方法可以做到这一点?

Is there any easy way to do this?

例如:

```{r, echo=FALSE, warning=FALSE, 
    fig.cap="Here is my really long caption.  It'd be nice to split this and other portions across lines"}
    print(plot(x=runif(100),y=runif(100)))
```

推荐答案

否，您不能在块选项中插入换行符.从手册:

No, you cannot insert line breaks in chunk options. From the manual:

块选项必须写成一行；块选项中不允许使用换行符

Chunk options must be written in one line; no line breaks are allowed inside chunk options

但是，如果您极希望在编辑器中使用整洁的格式，则可以通过其他变量绕行，但这会使代码膨胀很多:

However, if you desperately want neat formatting in the editor you could take a detour via an additional variable, but this inflates the code quite a lot:

---
output: 
  pdf_document:
    fig_caption: yes
---
```{r}
mycaption <- "This is my 
very long caption
that spans over
several lines.
(in the editor)"
```

```{r, fig.cap = mycaption}
plot(1)
```

使用选项eval.after，甚至可以在将其用作选项值的块中定义mycaption:

With the option eval.after it is even possible to define mycaption within the chunk that uses it as option value:

---
output: 
  pdf_document:
    fig_caption: yes
---
```{r}
library(knitr)
opts_knit$set(eval.after = "fig.cap")
```

```{r, fig.cap = mycaption}
mycaption <- "This is my 
very long caption
that spans over
several lines.
(in the editor)"

plot(1)
```

(我假设问题是关于代码在编辑器中的外观，而不是关于输出中的换行符.)

(I assume that the question is about how the code looks (in the editor) not about a line break in the output.)

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