kable unable to output unicode character in pdf_book (bookdown) - pdf

Question

I am trying to use the checkmark unicode character (\u2713) in a table rendered by kable in a bookdown project. A MWE consists in the following 2 files (index.Rmd, preamble.tex) part of the generated minimal bookdown project.
index.Rmd
---
title: "A Minimal Book Example"
subtitle: "subtitle"
lang: fr
author: "Yihui Xie"
date: "`r Sys.Date()`"
site: bookdown::bookdown_site
documentclass: book
mainfont: Arial
mathfont: Arial
bibliography: [book.bib, packages.bib]
biblio-style: apalike
link-citations: yes
subparagraph: yes
description: "This is a minimal example of using the bookdown package to write a book. The output format for this example is bookdown::gitbook."
---
```{r setup, include=FALSE}
# Set locale to french for month and day names (calendar plots)
Sys.setlocale(locale = 'French')
# Load all needed libraries
if(!require('pacman'))install.packages('pacman')
pacman::p_load(kableExtra)
```
(ref:O3) O~3~
# Prerequisites
✓
```{r stations-polluants, echo=FALSE}
stations_polluants_table <- data.frame(
stations = c("41B001", "41B004", "41B011", "41MEU1", "41N043", "41R001", "41R002", "41R012", "41WOL1", "Total / polluant"),
O3 = c("", rep("✓", 5), "", rep("\u2713", 2), "7")
)
kable(stations_polluants_table, col.names = c("Station", "(ref:O3)"), booktabs = T, align = "c", caption = "Caption text") %>%
row_spec(0, bold = T) %>%
row_spec(10, bold = T) %>%
collapse_rows(columns = 1, latex_hline = "major", valign = "top")
```
```{r include=FALSE}
# automatically create a bib database for R packages
knitr::write_bib(c(
.packages(), 'bookdown', 'knitr', 'rmarkdown'
), 'packages.bib')
```
preamble.tex
\usepackage{booktabs}
\newfontfamily{\unicodefont}{Arial Unicode MS}
\usepackage{newunicodechar}
\newunicodechar{✓}{{\unicodefont{✓}}}
By compiling in PDF with rmarkdown::render_site(output_format = 'bookdown::pdf_book', encoding = 'UTF-8') one can notice that ✓ is correctly rendered in the text, while it is replaced by <U+2713> in the generated table. I also tried to use \u2713 in the table without more success.
What am I doing wrong ? Please note that, even if the prefered output is PDF, I would also like to compile as gitbook (so Rmd files need to stay independent from the output format).
Many thanks.

Answer 1

After having a moment of clarity, the solution simply lies in using text references in bookdown, i.e. (ref:check) ✓ and use the reference within the table.
index.Rmd
```{r setup, include=FALSE}
# Set locale to french for month and day names (calendar plots)
Sys.setlocale(locale = 'French')
# Load all needed libraries
if(!require('pacman'))install.packages('pacman')
pacman::p_load(kableExtra)
```
(ref:O3) O~3~
# Prerequisites
✓
(ref:check) ✓
```{r stations-polluants, echo=FALSE}
stations_polluants_table <- data.frame(
stations = c("41B001", "41B004", "41B011", "41MEU1", "41N043", "41R001", "41R002", "41R012", "41WOL1", "Total / polluant"),
O3 = c("", rep("(ref:check)", 5), "", rep("(ref:check)", 2), "7")
)
kable(stations_polluants_table, col.names = c("Station", "(ref:O3)"), booktabs = T, align = "c", caption = "Caption text") %>%
row_spec(0, bold = T) %>%
row_spec(10, bold = T) %>%
collapse_rows(columns = 1, latex_hline = "major", valign = "top")
```
```{r include=FALSE}
# automatically create a bib database for R packages
knitr::write_bib(c(
.packages(), 'bookdown', 'knitr', 'rmarkdown'
), 'packages.bib')
```