displaced footnotes (and source_notes) using {gt} package in R when output pdf

Question

Trying to get to grips with the {gt} package, v0.9.

Outputting the following in pdf (html works) results in displaced footnotes/source_notes. I seem to fail to identify in the documentation how to ensure that (both) footnotes and source_notes are shown underneath the table.

library(tidyverse)
library(gt)

Building the table and it's {gt}-output

# taken from vignette
# take build-in island dataset and coerce to tibble and take top 10
islands_tbl <- 
  tibble(
    name = names(islands),
    size = islands
  ) |>
  arrange(desc(size)) |>
  slice(1:10)

# add header and footnote
# footnotes

tbl_experiment <- islands_tbl |> 
  gt() |> 
  tab_header(
      title = "Large Landmasses of the World",
      subtitle = "The top ten largest are presented"
  ) |>
  tab_footnote(
    footnote = "The Americas.",
    locations = cells_body(columns = name, rows = 3:4)
  ) |>  
  tab_source_note(
    source_note = md("(I am a source_note) Reference: McNeil, D. R. (1977) *Interactive Data Analysis*. Wiley.")
  )

tbl_experiment

This yield in pdf output:

Obviously, I could use {gt}'s gtsave() to store the table as a png (for example) and then include it again as an image in a qmd/Rmd file. While that workaround works ...

... I am trying to find out how to do this natively. Thanks for pointing me in the right direction.

Answer 1

The output you get is the expected output because quarto or rather the underlying pandoc relies on the longtable latex package and puts the footnotes inside a minipage.

There are many questions about footnotes being below tables in latex on tex.stackexchange.com but they generally rely on other table environments/packages or on complex tricks. The same is true regarding matching the width of the minipage and the table.

So the simplest solution would be to:

1. keep the tex file generated by quarto by adding keep-tex: true to your YAML preamble
2. match the width of table and minipage by:
   • setting the table to full width (which will match minipage width), OR
   • adapting the width of the minipage and table manually
3. compile the modified tex file (e.g., call tinytex::latexmk("filename.tex") from R)

To set the table to full width, replace \begin{longtable*}{lr} in your tex file by (source):

\setlength\LTleft{0pt}
\setlength\LTright{0pt}
\begin{longtable*}{@{\extracolsep{\fill}}lr@{}}

To adapt the width of the minipage and table you must center the minipage by enclosing in in \centerline{} and replace its width (\linewidth) by an absolute or relative width (e.g., 5cm or 0.5\linewidth, respectively). Then you may want to increase column width in the table (to get a wider table) by adding a specific width besides each column defined at the beginning of the longtable environment, so \begin{longtable*}{lr} would become \begin{longtable*}{l{2cm}r{50pt}} for example. Since this requires manual tweaking I would rather recommend the full-width approach.

Other solutions include:

• directly writing the table as latex in your quarto document and rely on other latex packages allowing for footnotes below the table such as threeparttable (not as difficult as it sounds)
• redefining some of the latex functions used directly in your Qmd preamble
• writing your own pandoc filter to change the processing of tables completely

Edit 08-08-2023: switching from gt to kableExtra

I just found a not-so-old Reddit thread where someone recommended kableExtra when using a pdf output and indeed it seems that kableExtra got you covered:

library(dplyr)
library(kableExtra)

islands_tbl <- 
  tibble(
    name = names(islands),
    size = islands
  ) |>
  arrange(desc(size)) |>
  slice(1:10)

# there is no subcaption so we have to define caption and subcaption as one
cap_text <- paste("\\large{Large Landmasses of the World} \\\\",
                  "\\small{The top ten largest are presented}")
# some wild escaping going on here to get proper formatting
# note that I add a manual linebreak, otherwise the table would be much wider
# to accommodate the long footnote
ref_text <- paste("(I am a source\\\\_note) Reference: McNeil, D. R. (1977) \n",
                  "\\\\textit{Interactive Data Analysis}. Wiley.")

islands_tbl |>
  mutate(name = ifelse(grepl("America",name,ignore.case = T),
                       paste0(name,footnote_marker_number(1, "latex")),
                       name)) |> # adding the footnote markers where necessary
  kbl(caption = cap_text,
      booktabs = T,
      linesep = "", # if unspecified booktabs adds spacing after every 5th line
      escape = F) |> # you need to set escape to FALSE so that the latex commands work
  kable_styling(latex_options = "hold_position") |>
  footnote(general = linebreak(ref_text, double_escape = T),
           number = "The Americas.",
           footnote_order = c("number","general"),
           general_title = "",
           escape = F)