knitr-从`purl(...)`中排除大块吗?

问题描述

当我整理/纠缠文档以将R块提取到脚本中时，有什么方法可以实现:

When I purl/tangle a document to extract the R chunks into a script, is there any way to:

• 排除任意块(按名称说)?
• 如果不是，则排除eval=F块(或者也许我可以定义块挂钩/选项include=F)?

• exclude an arbitrary chunk (by name say)?
• if not, exclude a chunk if eval=F (or perhaps I can define a chunk hook/option include=F)?

例如，假设我有以下Rmd:

For example, suppose I have the following Rmd:

```{r setup, echo=F}
library(MASS)
```
First, we perform the setup (assume for some reason I need to evaluate `setup`
silently before I wish to display the chunk to the user, hence the repetition)
```{r setup, eval=F}
```

Here's the function I've been explaining:
```{r function}
plus <- function (a, b) a + b
```

And here's an example of its use:
```{r example}
plus(1, 2)
```

缠结的脚本如下所示:

## @knitr setup, echo=F
library(MASS)

## @knitr setup, eval=F
library(MASS)

## @knitr function
plus <- function (a, b) a + b

## @knitr example
plus(1, 2)

我有一个想法，因为我不是要评估特定的块，因此至少它们不应出现在输出中(在上面的示例中，第二个setup块).

I have the idea that since I didn't want particular chunks to be evaluated, they at the very least should not appear in the output (in the example above, the second setup chunk).

另外，对于那些纠结的输出，将一些块标记为不可见"对我来说很好.我不想在输出脚本中使用example块(出于文档目的，它在Rmd中很好用，但是如果我想使用source('myfile.r') >功能，而不必担心这些额外的示例会执行.目前，我纠结Rmd，然后手动编辑出脚本中不需要的部分，这似乎与只写原则背道而驰一个Rmd，无需额外的工作即可提供文档和脚本.)

Additionally it would be nice for me to mark some chunks as "invisible" with respect to the tangled output. I don't want the example chunk in my output script (it was nice in the Rmd for purposes of documentation, but I want to be able to tangle the Rmd and then just source('myfile.r') if I wish to use the plus function, without having to worry about these extra examples executing. Currently I tangle the Rmd and then manually edit out the chunks I don't want out of the script, which seems against the principle of just writing the one Rmd which will provide both documentation and script without extra effort.)

推荐答案

由于 knitr 1.3，有一个新块选项purl = TRUE/FALSE，它允许为purl()包括/排除某些代码块.

Since knitr 1.3, there is a new chunk option purl = TRUE/FALSE that allows one to include/exclude certain code chunks for purl().

```{r test, purl=FALSE}
library(MASS)
```

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