Adding a letter to all table numbers in RMarkdown

Question

I'm using RMarkdown to create Supplementary documents for a paper. These supplements contain many tables. Let's call these documents Supplement A and Supplement B. I want the table numbering to reflect the supplement letter, that is, Table A1 or Table 1A for the first table in Supplement A and so on for all tables.

How can I modify the table numbering to add a letter into the table numbering schema?

Here's an example that will produce a table with normal numbering:

---
title: "Supplement A"
output: pdf_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
library(knitr)
library(kableExtra)
```

```{r cars}
kable(mtcars[1:5, ], booktabs=TRUE, caption="MTCars") %>%
  kable_styling(latex_options="hold_position", position="left")
```

Answer 1

An inelegant solution using the captioner package (details provided here: https://datascienceplus.com/r-markdown-how-to-number-and-reference-tables/) can create captions and insert them manually just before the code chunk. Combining this with the Latex package caption makes it possible to remove the automatic table naming and numbering if the caption is generated within the code chunk (How to suppress automatic table name and number in an .Rmd file using xtable or knitr::kable?). I've done this in the YAML with \captionsetup[table]{labelformat=empty}, but it can be done in the document body also. Either way, the caption can then be generated within the code chunk, which was important in my case.

This solution stops bookdown referencing from working (because labelformat cannot be empty), but a workaround for table referencing was provided in the link for using the captioner package (and is included below).

---
title: "Supplement A"
header-includes:
  - \usepackage{caption}
    \captionsetup[table]{labelformat=empty}
output: pdf_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
library(knitr)
library(kableExtra)
library(captioner)
library(stringr)
```

```{r captions}
# Create the caption(s)
caption <- captioner("Table A", FALSE)
tab_1_cap <- caption("Tab_1", "MTCars")

# Create a function for referring to the tables in text
ref <- function(x) str_extract(x, "[^:]*")
```

The following table is `r ref(tab_1_cap)`.

```{r cars}
kable(mtcars[1:5, ], booktabs=TRUE, caption=tab_1_cap) %>%
  kable_styling(latex_options="hold_position", position="left")
```

Answer 2

An alternative solution is avaiable via LaTeX. Simply add the following somewhere in the body of the document.

\def\figurename{Figure A}
\def\tablename{Table A}

To reference a table or figure in text use, e.g., Table A\@ref(tab:label), after defining the table label as normal.

This is also not a perfect solution because it will produce, e.g., Table A 1 instead of Table A1 (i.e., with a space), but it is much quicker and easier than my earlier solution.

---
title: "Supplement A"
output: bookdown::pdf_document2
toc: false
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
library(knitr)
library(kableExtra)
library(bookdown)
```

\def\figurename{Figure A}
\def\tablename{Table A}

See Table A\@ref(tab:cars) for something about cars.

(ref:cars) Table caption

```{r cars}
kable(mtcars[1:5, ], booktabs=TRUE, caption="(ref:cars)") %>%
  kable_styling(latex_options="hold_position", position="left")
```

Answer inspired by: Figure name in caption using RMarkdown