在R Markdown中为代码块添加换行符

Question

我正在使用带有R Markdown的knitr包来创建HTML报告。使用'+'时，我在将代码保持在单独的行上时遇到了一些麻烦。

例如，

```{r}
ggplot2(mydata, aes(x, y)) +
   geom_point()
```

将返回以下HTML文档

ggplot2(mydata, aes(x, y)) + geom_point()

通常这很好，但是一旦我开始添加额外的行就会出现问题，我希望将这些行分开以使代码更容易理解。运行以下内容：

```{r}
ggplot2(mydata, aes(x, y)) +
   geom_point() +
   geom_line() +
   opts(panel.background = theme_rect(fill = "lightsteelblue2"),
        panel.border = theme_rect(col = "grey"),
        panel.grid.major = theme_line(col = "grey90"),
        axis.ticks = theme_blank(),
        axis.text.x  = theme_text (size = 14, vjust = 0),
        axis.text.y  = theme_text (size = 14, hjust = 1.3))
```

将导致所有代码出现在一行中，使其更难以遵循：

ggplot2(mydata, aes(x, y)) + geom_point() + geom_line() + opts(panel.background = theme_rect(fill = "lightsteelblue2"), panel.border = theme_rect(col = "grey"), panel.grid.major = theme_line(col = "grey90"), axis.ticks = theme_blank(), axis.text.x  = theme_text (size = 14, vjust = 0), axis.text.y  = theme_text (size = 14, hjust = 1.3))

非常感谢任何解决此问题的帮助！

Answer 1

尝试chunk选项tidy = FALSE：

```{r tidy=FALSE}
ggplot2(mydata, aes(x, y)) +
  geom_point() +
  geom_line() +
  opts(panel.background = theme_rect(fill = "lightsteelblue2"),
       panel.border = theme_rect(col = "grey"),
       panel.grid.major = theme_line(col = "grey90"),
       axis.ticks = theme_blank(),
       axis.text.x  = theme_text (size = 14, vjust = 0),
       axis.text.y  = theme_text (size = 14, hjust = 1.3))
```

Answer 2

我发现将块的“整洁”设置更改为false的一种方法是添加中间命令注释。这似乎使整个块处理为非整洁，从而尊重您在代码中拥有（或没有）的换行符。不幸的是，这不会在特定位置（对于特定行）添加换行符。

示例：将下面的原始文本复制到Rmd文件中并使用knitr进行处理。

整理（即默认）

输入

```{r eval=FALSE}
# Line comments do not seem to change tidiness.
list(
    sublist=list( 
        suba=10, subb=20 ),
    a=1,
    b=2 ) # End of line comment does not seem to change tidiness.

list(
    sublist=list( 
        suba=10, subb=20 ),
    a=1,
    b=2 )

```

输出

# Line comments do not seem to change tidiness.
list(sublist = list(suba = 10, subb = 20), a = 1, b = 2) # End of line comment does not seem to change tidiness.

list(sublist = list(suba = 10, subb = 20), a = 1, b = 2)

Untidied

输入

```{r eval=FALSE}
list(
    sublist=list( 
        suba=10, subb=20 ),
    a=1, # Mid-command comment seems to "untidy" the chunk.
    b=2 )

list(
    sublist=list( 
        suba=10, subb=20 ),
    a=1,
    b=2 )

```

输出

list(
    sublist=list(
        suba=10, subb=20 ),
    a=1, # Mid-command comment seems to "untidy" the chunk.
    b=2 )

list(
    sublist=list(
        suba=10, subb=20 ),
    a=1,
    b=2 )