r - 在Knitr中的行之间拆分R block 头

Question

当我在R块 header 中插入长标题等内容时，能够将 header 拆分为多行会很好。

有没有简单的方法可以做到这一点？

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)))
```

Answer 1

不可以，您不能在块选项中插入换行符。从the manual:

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

但是，如果您非常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:

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

---
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，而不是输出中的换行符。)