How to doublespace a sidewaystable using setspace?

Question

As a follow-up to a previous question, How to doublespace a table using setspace?, I found that the solution is not compatible with the sidewaystable environment defined in the rotating package.

I have modified the example in the answer from the previous question to demonstrate:

\documentclass{article}
\usepackage{amsmath}
\usepackage{setspace}
\usepackage{lipsum}
\usepackage{rotating}
\newcommand\Factor{1.9}

\makeatletter
\def\@xfloat#1[#2]{\ifhmode \@bsphack\@floatpenalty -\@Mii\else
   \@floatpenalty-\@Miii\fi\def\@captype{#1}\ifinner
      \@parmoderr\@floatpenalty\z@
    \else\@next\@currbox\@freelist{\@tempcnta\csname ftype@#1\endcsname
       \multiply\@tempcnta\@xxxii\advance\@tempcnta\sixt@@n
       \@tfor \@tempa :=#2\do
                        {\if\@tempa h\advance\@tempcnta \@ne\fi
                         \if\@tempa t\advance\@tempcnta \tw@\fi
                         \if\@tempa b\advance\@tempcnta 4\relax\fi
                         \if\@tempa p\advance\@tempcnta 8\relax\fi
         }\global\count\@currbox\@tempcnta}\@fltovf\fi
    \global\setbox\@currbox\vbox\bgroup
    \def\baselinestretch{\Factor}\@normalsize
    \boxmaxdepth\z@
    \hsize\columnwidth \@parboxrestore}
\makeatother

\begin{document}
\begin{spacing}{\Factor}
\lipsum[1]
\begin{sidewaystable}[ht]
\begin{tabular}{rlll}
  \hline
 & col1 & col2 & col3 \\ 
  \hline
  50 & 19 & 7 & 26 \\ 
  100 & 10 & 20 & 29 \\ 
  150 & 1 & 7 & 2 \\ 
  200 & 0 & 0 & 10 \\ 
\hline
\end{tabular}
\end{sidewaystable}
\end{spacing}
\end{document}

Running pdflatex on this document returns the error:

! Extra }, or forgotten \endgroup.
\color@endbox ->\egroup 

l.40 \end{sidewaystable}

How can I get around this?

Answer 1

I don't understand. What do you want to be doublespaced? Why all that code? Simply put \doublespacing after \begin{sidewaystable}[ht]

\documentclass{article}
\usepackage{amsmath}
\usepackage{setspace}
\usepackage{lipsum}
\usepackage{rotating}
%
\begin{document}
\lipsum[1]
\begin{sidewaystable}[ht]
\doublespacing %%% <--- here
\begin{tabular}{rlll}
  \hline
 & col1 & col2 & col3 \\
  \hline
  50 & 19 & 7 & 26 \\
  100 & 10 & 20 & 29 \\
  150 & 1 & 7 & 2 \\
  200 & 0 & 0 & 10 \\
\hline
\end{tabular}
\end{sidewaystable}
\end{document}

Update:

If you want to control things from the preamble, you can use etoolbox package as below:

\documentclass{article}
\usepackage{amsmath}
\usepackage{setspace}
\usepackage{lipsum}
\usepackage{rotating}
\usepackage{etoolbox}   %%% <----here
\AtBeginEnvironment{tabular}{\doublespacing}    %%% <---- and here
%
\begin{document}
\lipsum[1]
\begin{sidewaystable}[ht]
\begin{tabular}{rlll}
  \hline
 & col1 & col2 & col3 \\
  \hline
  50 & 19 & 7 & 26 \\
  100 & 10 & 20 & 29 \\
  150 & 1 & 7 & 2 \\
  200 & 0 & 0 & 10 \\
\hline
\end{tabular}
\end{sidewaystable}
\end{document}

Before the tabular environment, we have issued the command \doublespacing. This approach affects all tabular environments though.

Answer 2

I agree with the other answer that redefining should not be necessary especially redefining a core LaTeX feature like float handling seems very brave.

However you get the error because you have

   \global\setbox\@currbox\vbox\bgroup

Which is how it was in LaTeX2.09 last millenium. The LaTeX2e definition of \@xfloat ends

  \global \setbox\@currbox
    \color@vbox
      \normalcolor
      \vbox \bgroup
        \hsize\columnwidth
        \@parboxrestore
        \@floatboxreset
}

Which means, if you have the color package loaded, that your redefinition has the wrong number of groups, and is not color safe, so you get:

! Extra }, or forgotten \endgroup.
\color@endbox ->\egroup