pdf footnotes

[ggrothendieck]

In attempting to get pdf footnotes without using the last row of the table for that, the following seems to work but had to descend to latex level and also there are some gsub's that are pretty ugly. After trying many variations this was the one that worked the best. I wonder if huxtable could make this a bit easier. For example, maybe to_latex could have an argument that instructs it not to generate the junk that the gsub's remove.

To run this put it in a file myfile.Rmd and then run render("myfile.Rmd")

---
title: "test footnotes"
output:
  pdf_document:
    keep_tex: true
header-includes:
  - \usepackage{threeparttable}
  - \usepackage{caption}
  - \usepackage{calc}
  - \usepackage{hhline}
  - \usepackage{colortbl}
  - \usepackage{tabularx}
---

\newcommand{\htwithnotes}[3]{%
\begin{center}
\begin{threeparttable}
\captionof{table}{#3}
#1
\begin{tablenotes}[flushleft]
\footnotesize
#2
\end{tablenotes}
\end{threeparttable}
\end{center}
}

```{r setup, include=FALSE}
library(huxtable)
options(huxtable.latex_use_fontspec = FALSE)

ht_pdf <- function(ht, notes = "", caption = "") {
  
  safe_caption <- sanitize(caption, type = "latex")
  safe_notes   <- sanitize(notes, type = "latex")
  
  escape_contents(ht) <- TRUE
  
  latex_float(ht) <- "none"
  table_environment(ht) <- NA
  
  ltx_body <- to_latex(ht, tabular_only = TRUE)
  
  ltx_body <- gsub("```\\{=latex\\}", "", ltx_body)
  ltx_body <- gsub("```", "", ltx_body)
  
  formatted_notes <- paste0("\\item ", safe_notes, collapse = "\n")
  
  res <- sprintf("\\htwithnotes{%s}{%s}{%s}", ltx_body, formatted_notes, safe_caption)
  knitr::asis_output(res)
}
```

## Table

```{r generate_table, echo = FALSE, results = 'asis'}

ht <- as_hux(BOD, add_colnames = TRUE) |>
  set_align(everywhere, everywhere, "center") |>
  set_all_borders(0.5) |>
  set_bold(1, everywhere, TRUE) |>
  set_background_color(1, everywhere, "grey90") |>
  set_width(0.9)

notes <- c("Some note", "Some other note")

ht_pdf(ht, notes = watchlist_notes, caption = "My caption")
```

[hughjonesd]

How's this as a workaround in a Rmd document?

```{r setup}
library(huxtable)

jams[1,1] <- "Jams\\footnotemark"
escape_contents(jams)[1, 1] <- FALSE
jams
```


\footnotetext{Some footnote text}

[ggrothendieck]

The jams example puts the footnote at the bottom of the page. ht_pdf puts it at the bottom of the table.

[hughjonesd]

I see. So is there a reason you don't want to do this simply by adding a row at the bottom? Is it conceptual or aesthetic reasons?

[ggrothendieck]

It is because the amount of code just to add a footnote seems excessive because you have to override the attributes of the other rows and there is further problems in getting a width that works for both. See #364 for an example. I am not the only one who has noticed this. Look at #228

[hughjonesd]

Hmm, OK. I think the answer is "fix #228".

One possibility:

(1) change the underlying mechanism to store footnotes as table attributes
(2) allow different ways to print this (\footnote, maybe title attributes in html, typst #footnote or tblr package etc.

A problem with this is how to denote a footnote marker. Different output formats do this in their own ways, I don't much want to reinvent any of them.

[hughjonesd]

Running the command above gives me:

Whereas just running this:

```{r generate_table, echo = FALSE, results = 'asis'}
library(huxtable)
ht <- as_hux(BOD, add_colnames = TRUE) |>
  set_align(everywhere, everywhere, "center") |>
  set_all_borders(0.5) |>
  set_bold(1, everywhere, TRUE) |>
  set_background_color(1, everywhere, "grey90") |>
  set_width(0.9) |> 
  add_footnote("Some note\nSome other note")

ht
```

gives me:

At the moment, I'm not convinced that the difference is enough to motivate a new feature. In particular (see also #364) I am quite in favour of having table notes that have the same width as the table, and doing this by using a table row seems a reasonable hack.

[ggrothendieck]

Let me change the focus slightly. Suppose one wants to create their own latex based function, not necessarily for table footnotes but it could be anything, and still use quick_pdf so they can test it faster before putting it in an Rmd. Would there be a feature that would allow this?

[hughjonesd]

I would use to_latex()/print_latex(), perhaps with tabular_only = TRUE, then customize the latex output, then use standard R tools for compiling tex. I don't have plans to make quick_pdf() and friends handle arbitrary latex strings.