cite figure in other figure caption in markdown to pdf - r

Question

Using R markdown with PDF output, I want to cite a figure into another figure caption. I also want to cite a BibTex reference in the caption. Any ideas? Here's an example of code:
---
title: "Untitled"
author: "me"
date: "today"
output:
pdf_document:
latex_engine: lualatex
number_sections: no
linestretch: 1.5
bibliography: input/Library.bib
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, warning = FALSE, message = FALSE)
```
```{r}
df <- mtcars
library(ggplot2)
```
```{r, fig.cap="some stuff"}
ggplot(df, aes(cyl, mpg)) + geom_point()
```
```{r, fig.cap="some more stuff. here I'd like to cite figure 1. I would also like a BibTex citation"}
ggplot(df, aes(cyl, hp)) + geom_point()
```

Answer 1

In my experience cross-referencing works better when one uses bookdown::pdf_document2 or bookdown::html_document2. Note that it makes sense to name the chunk that produces the figure since that name is used in the label used for referencing:
---
title: "Untitled"
author: "me"
date: "today"
output:
bookdown::pdf_document2:
latex_engine: lualatex
number_sections: no
bookdown::html_document2:
default
linestretch: 1.5
bibliography: packages.bib
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, warning = FALSE, message = FALSE)
knitr::write_bib(c(.packages()), 'packages.bib')
```
```{r}
df <- mtcars
library(ggplot2)
```
```{r stuff, fig.cap="some stuff"}
ggplot(df, aes(cyl, mpg)) + geom_point()
```
```{r, fig.cap="some more stuff. here I'd like to cite figure \\#ref(fig:stuff). I would also like a BibTex citation [#R-base]"}
ggplot(df, aes(cyl, hp)) + geom_point()
```
For the BibTeX reference I am using an automatically created one, but the adaption to your case should be obvious.