在 RMarkdown 文档中包含 YAML 文件

Question

I have an RMarkdown document that includes an example YAML file, currently in the form:

```{yaml}
name: r40_tidyverse
channels:
  - conda-forge
  - nodefaults
dependencies:
  - r-base=4.0
  - r-tidyverse
```

This renders (knits) into HTML with nice YAML syntax highlighting.

Knitted Result

Instead of the above, I would like to include it as an external YAML file, say at envs/r40_tidyverse.yaml . I have tried using

```{yaml child="envs/r40_tidyverse.yaml"}
```

While this correctly loads the file, the resulting HTML is merely a <p></p> element with the contents of the file located within it.

Knitted Result

This is not desirable.

How can one load an external YAML file into an RMarkdown document and achieve syntax highlighting similar to when including a YAML code chunk directly?

Answer 1

I think the easiest way is that you read the external file in an inline R expression, eg,

```yaml
`r xfun::file_string('envs/r40_tidyverse.yaml')`
```

Note that you should not use ```{yaml} (ie, do not add {} to yaml ), because that would change its meaning to knitr :

• With curly braces, it means a code chunk, and a knitr language engine needs to evaluate the code chunk (but there is not a yaml engine yet, and your first example worked just by chance).
• Without curly braces, it means a normal code block, which will not be processed by knitr .