Use of inline r code in code-chunk options fig-cap and tbl-cap

[larnsce]

Description

I would like to use dynamic figure and table captions in quarto documents, e.g.

---
format: html
params
  year: 2022
---

In @fig-requests-year the ...

```{r}
#| label: fig-requests-year
#| fig-cap: "Number of requests per year in `r params$year`."

fig_requests

[mcanouil]

You have to use Quarto syntax as described in https://quarto.org/docs/computations/r.html#chunk-options.

#| fig-cap: !expr 'paste("Air", "Quality")'

I am changing this discussion to Q&A.

[larnsce]

Thank you for your quick and helpful feedback.

[jkylearmstrong]

Hey @mcanouil, I am very confused by this note:

the !expr syntax is an example of a YAML “tag” literal, and it can be unintuitive. !expr needs to be followed by a single YAML “flow scalar”: see the YAML spec for details on how double-quoted, single-quoted, and unquoted strings work.

when I am making a fig-cap or tbl-cap within a child document, I might want to reference a corresponding table or figure in addition to using an r code value?

Would the corresponding code look like this:

#| label: tbl-{{var}}
#| fig-cap: !expr 'paste("Corresponding to ", @fig-{{var}}, " we find the mean is, ", mean_value , ".)'

A few more examples would be helpful in the documentation.

Thanks!

[mcanouil]

This thread is very old.
As with recent version of Quarto, I would highly recommend to avoid !expr which is knitr specific and can lead to very weird syntax.

Use the cross-reference div syntax and inline code.

::: {#<prefix>-<whatever-name>}

```{language}
Code
```

The caption with `{language} code`.
::: 

@fig-{{var}} is not an R expression in your case.
What you provide to !expr still needs to be valid R code.

[baptiste]

You can also use the older knitr syntax, which is less constrained by Yaml limitations

---
title: "Untitled"
format: html
params:
  year: 2022
---

In @fig-requests-year the ...

```{r, fig.cap=glue::glue("Number of requests per year in {params$year}.")}
#| label: fig-requests-year

plot(1,1)
```

[mcanouil]

You should not mixed YAML and inline code cell syntax, even in rmarkdown it is not recommended.

Also Quarto recommends YAML syntax which is the syntax fully supported.

[jkylearmstrong]

Thanks @mcanouil I'll try it out, I understand the post is old but it's also where google directed me! So hopefully, it will help others in the future.

[mcanouil]

It's been a very long time since I relied on Google indexing to find something.
GitHub has a pretty good (in my opinion) search engine and here, on Quarto CLI repository, we try to label everything to help finding useful tips, workaround, etc., so I suggest to use it for Quarto related matters.
I strongly think the best resources for Quarto are:

• GitHub Discussions
• https://quarto.org
• GitHub Issues