Using \multicolumn inside overlay

Question

How can I use \multicolumn together with overlays?

\multicolumn fails if there is an overlay before it or if \multicolumn is used inside an overlay.

I actually want to do the last. \only<2>{\multicolumn{2}{c}{three}\\}

MWE:

\documentclass{beamer}

\usepackage{siunitx}

\begin{document}

\begin{frame}
\begin{tabular}{*{4}{|>{$}{c}<{$}}|}
\hline
a & b & c & d\\
\hline
1 & 2 & 3 & 4\\
\hline
%TODO following works
\multicolumn{2}{c}{one}\\
\only<2>{one\\}
%TODO following doesn't work
%\only<2>{two\\}
%\multicolumn{2}{c}{two}\\
%TODO following doesn't work
%\only<2>{\multicolumn{2}{c}{three}\\}
\end{tabular}
\end{frame}

\end{document}

why would you want \multispan and not \multicolumn? \multispan comes from plain tex and was never intended to be used in tabular directly — David Carlisle, Nov 09 '17 at 16:29
don't believe everything you read on the internet:-) I left a comment on that answer — David Carlisle, Nov 09 '17 at 16:44
@DavidCarlisle Thanks for your help so far, but also \multicolumn doesn't work inside an overlay — user1, Nov 11 '17 at 18:43
@DavidCarlisle \only<2>{\\[-\normalbaselineskip]\multicolumn{2}{c}{three}} compiles without errors, but the vertical lines of the "jumped" line are overprinted by three — user1, Nov 11 '17 at 18:51
@DavidCarlisle do you know a nice command to go back to the rowstart, so I don't have to calculate it (see my answer) — user1, Nov 11 '17 at 20:09
you need of course to make sure each layer has the same numer of \\ so remove the one at the end of the previous row. — David Carlisle, Nov 11 '17 at 20:12
@DavidCarlisle actually there should be a \hline after my previous row. I solved this problem (see comment on you answer) — user1, Nov 11 '17 at 21:01

score 2 · Answer 1 · answered Nov 11 '17 at 20:23

2

As far as I can tell, you want something like

\documentclass{beamer}

\usepackage{siunitx}


\begin{document}

\begin{frame}
\begin{tabular}{*{4}{|>{$}{c}<{$}}|}
\hline
aaa & b & c & d\\
\hline
1 & 2 & 3 & 4\\
\hline
\multicolumn{1}{l}{th}
\only<1>{\\\multicolumn{2}{l}{}}
\only<2>{\\\multicolumn{2}{l}{th}}
\end{tabular}
\end{frame}

\end{document}

Or the following, which makes the same output in this case.

\documentclass{beamer}

\usepackage{siunitx}



\begin{document}

\begin{frame}
\begin{tabular}{*{4}{|>{$}{c}<{$}}|}
\hline
aaa & b & c & d\\
\hline
1 & 2 & 3 & 4\\
\hline
\multicolumn{1}{l}{th}\\
\multicolumn{2}{l}{\only<2>{th}}
\end{tabular}
\end{frame}

\end{document}

answered Nov 11 '17 at 20:23

David Carlisle

757,742

Your second solution doesn't work nice, if you change it to something like \multicolumn{2}{l}{\only<2>{th2}}\\ \multicolumn{3}{l}{\only<3>{th3}} by this there if an empty line (or one have to get the first parameter get calculated basing on \onlys) – user1 Nov 11 '17 at 20:56
Your first solution is fine. Thanks. To achieve, what I actually want, just delete \\ \hline \multicolumn{1}{l}{th} and add \hline before the two \multicolumns like \\\hline\multicolumn – user1 Nov 11 '17 at 20:58

score 1 · Answer 2 · answered Nov 11 '17 at 20:08

Right now I got:

\documentclass{beamer}

\usepackage{siunitx}

\newlength{\widthoffirstcolumn}
\settowidth{\widthoffirstcolumn}{%
\begin{tabular}{>{$}{c}<{$}}% %here are not | on purpose (still not the exact indent)
aaa\\
1
\end{tabular}%
}

\begin{document}

\begin{frame}
\begin{tabular}{*{4}{|>{$}{c}<{$}}|}
\hline
aaa & b & c & d\\
\hline
1 & 2 & 3 & 4\\
\hline
\multicolumn{1}{l}{th}\\ %only for testing the indent of next row
\multicolumn{1}{c}{}\only<2>{&\multicolumn{2}{l}{\hspace{-\widthoffirstcolumn}th}\\}
\end{tabular}
\end{frame}

\end{document}

The \multicolumn{1}{c}{} is for not getting vertical lines

The \hspace{-\widthoffirstcolumn} goes back the to start of the row

I'm not sure if this is a nice solution, but it works... (the rowstart isn't calculated exactly)

Using \multicolumn inside overlay

2 Answers2

Linked