Setting caption to be wider than table

[iagomosqueira]

When outputting some narrow tables to pdf, I would like the caption to be wider than the table, rather than ending up in multiple lines. I might have missed something but could not get it to be so.

Tried setting the parbox width in label_string but I think it is not working as hoped as caption is set inside the tabular array.

[vincentarelbundock]

Which output format are you saving to?

[iagomosqueira]

Generating pdf via pandoc

[vincentarelbundock]

Hmm, ok. I'm not sure how to do this. I gave a quick look at the tabularray manual but couldn't find an answer immediately.

You may be able to define a custom caption theme as in this example (supplied by a LLM).

I'll be curious to know if you can make this work.

LLM example

For longtblr/talltblr, the caption is part of tabularray’s table head templates, and tabularray sets that head’s \hsize/\linewidth to the table width. So a narrow table makes the default caption wrap at the narrow table width. The fix is to override the caption template and put the caption text in a wider \parbox. The tabularray docs show that captions are built from caption-tag, caption-sep, and caption-text, and that continuation captions use capcont; the source also shows the head/foot \hsize is set to \lTblrTableWidthDim.

Put this in the preamble:

\newlength{\tblrcaptionwidth}
\setlength{\tblrcaptionwidth}{\textwidth} % choose .8\textwidth, \linewidth, etc.

\NewTblrTheme{widecaption}{
  \DeclareTblrTemplate{caption}{wide}{%
    \makebox[\linewidth][c]{%
      \parbox{\tblrcaptionwidth}{%
        \centering
        \UseTblrTemplate{caption-tag}{default}%
        \UseTblrTemplate{caption-sep}{default}%
        \UseTblrTemplate{caption-text}{default}%
      }%
    }%
    \par
  }%

  % For continuation pages of longtblr:
  \DeclareTblrTemplate{capcont}{wide}{%
    \makebox[\linewidth][c]{%
      \parbox{\tblrcaptionwidth}{%
        \centering
        \UseTblrTemplate{caption-tag}{default}%
        \UseTblrTemplate{caption-sep}{default}%
        \UseTblrTemplate{caption-text}{default}%
        \UseTblrTemplate{conthead-pre}{default}%
        \UseTblrTemplate{conthead-text}{default}%
      }%
    }%
    \par
  }%

  \SetTblrTemplate{caption}{wide}
  \SetTblrTemplate{capcont}{wide}
}

Then use it like this:

\begin{longtblr}[
  theme = widecaption,
  caption = {A very long caption that should use the full text width, not the table width},
  label = {tab:example},
]{
  colspec = {cc},
  hlines,
}
A & B \\
C & D \\
\end{longtblr}

Change

\setlength{\tblrcaptionwidth}{\textwidth}

to whatever width you want. With [c] in \makebox[\linewidth][c], the wider caption is centered over the table. Use [l] if you want it aligned with the table’s left edge and extending to the right.