6.18 FAQ

Q: How to add comments in Quarto markdown?
A: Use HTML comment syntax: 

Multiline comment:

<!--
your comment goes here
-->

Q: How to put shared chunk options setup in one file?
A: Put your shared chunk options in a separate file, e.g., _setup.qmd, then include it in your .qmd files using {{< include >}} shortcode:

{{< include _setup.qmd >}}

The undersore in the file name indicates that it is a helper file that is not meant to be rendered on its own. It is just a nice convention for the included files. You should always use an underscore prefix with included files so that they are automatically ignored (i.e. not treated as standalone files) by a quarto render of a project.

I think this is the most concise way to include shared chunk options. Other options: put the shared chunk options in a separate .R file and source it in the setup chunk of your .qmd file:

```{r setup, include=FALSE} 
source("_setup.R")
```

Note that you cannot use {{< include >}} shortcode to execute an .R file.

If you have

{{< include _setup.R >}}

the _setup.R will NOT be executed it NOT inserted. For inserting the content of an .R file, you need to quote the shortcode with triple backticks as follows.

Another common use for {{< include >}} shortcode is to print verbatim content from an external file. For example, you can use it to include a code snippet from an external file:

```r 
{{< include _demo.R >}}
```

You can use other language tags, e.g., python,

```python 
{{< include _demo.py >}}
```

The source code blocks ensure that the code is included as non-executed examples.

Load .txt files as verbatim text:

<pre style='white-space: pre-wrap;'>
{{< include ../output/data_description.txt >}}
</pre>

This is equivalent to

```{r, output="asis"} 
f_name <- file.path(out_dir, "0-0_data_description.txt")
cat("<pre style='white-space: pre-wrap;'>", paste(readLines(f_name), collapse = "\n"), "</pre>")
```

References: