[Tex/LaTex] Set multicolumn width to default table width

multicolumntables

I have a two column table with a single multicolumn spanning both of them. The text on that multicolumn is rather long so I need to set its width so it wraps around. I can set the width with \multicolumn{2}{p{whatever}}{text} but what should I set "whatever" to? What is the actual width of a table? Is there a variable holding that value?

I first thought to use \textwidth but that's not it. Building the document on draft mode shows that it's going out a tiny bit. The following table should show my problem. In draft mode will display a black box on its side.

\begin{tabular}{l l}
  \toprule
  \multicolumn{2}{p{\textwidth}}{\lipsum[1]} \\
  \bottomrule
\end{tabular}

I do have more rows, I'm just keeping the example simple. I'm using the memoir document class. The actual text inside the multicolumn is using the seqsplit package.

EDIT: I should have been more specific with the question. The only row that would make the table go over the limit is the one that I'm also trying to limit. And by limit I mean, so I don't get an overfull warning.

So my question can be better rephrased as how to find the available space for a table so it is not overfull?

Best Answer

The space available isp{\dimexpr\textwidth-2\tabcolsep\relax} due to the column padding LaTeX applies, assuming you have \noindent\begin{tabular} otherwise the table itself will be offset by \parindent.

However if the span is wider than the columns it spans, TeX puts all the extra width into the last column. If that is a problem, edit your example to be a complete (small) document that shows the problem.

Related Solutions

[Tex/LaTex] \parbox “textwidth” for the combined width of a subset of table cells

You measure the width of the columns by catching them into a box using the lrbox environment and then measuring and accumulating their width (and the column separation between).

Using special column types defined with the help of the array package makes this actually very easy to handle in the tabular.

\documentclass{article}

\usepackage{array}
\newlength{\mycolwidth}
% First column (re-)sets to width.
\newcolumntype{F}{>{\global\mycolwidth=-\tabcolsep\addmycolwidth}c<{\endaddmycolwidth}}
% All other to be measured cells have type `C` which uses `c` internally:
\newcolumntype{C}{>{\addmycolwidth}c<{\endaddmycolwidth}}
% The `P` type then uses the saved width:
\newcolumntype{P}{p{\mycolwidth}}

\newsavebox{\mycolwidthbox}% box to save cells in
\newenvironment{addmycolwidth}{%
   \begin{lrbox}{\mycolwidthbox}%% catch cell content into a box
}{%
   \end{lrbox}%
   \usebox{\mycolwidthbox}%% place cell content back
   % Add width and column sep: (globally because this code is still executed inside the cell which acts like a group)
   \global\advance\mycolwidth by \wd\mycolwidthbox
   \global\advance\mycolwidth by \tabcolsep
}

\begin{document}
\begin{tabular}{c|F|C|C|C|} \cline{2-5}
\textbf{A} & first & second & third & fourth, of variable length \\ \cline{2-5}
& \multicolumn{4}{P|}{fifth, also of highly variable length but
   long enough to need to wrap.} \\ \cline{2-5}
\end{tabular}

\begin{tabular}{c|F|C|C|C|} \cline{2-5}
\textbf{B} & first & second & third & fourth, of much much longer length \\ \cline{2-5}
&  \multicolumn{4}{P|}{fifth, also of highly variable length but
   long enough to need to wrap.} \\ \cline{2-5}
\end{tabular}
\end{document}

Result:

Resulting tables

[Tex/LaTex] Table column widths disproportionate due to multicolumn cell being too long

It's a feature of the \halign primitive:

enter image description here

\documentclass{article}
\usepackage{tabularx}
\begin{document}

\centering
\parskip2\baselineskip

\begin{tabular}{*5{c}}
\multicolumn{5}{c}{This is a piece of text. The longer it is, the longer the last column.} \\ 
1 & 2 & 3 & 4 & 5 \\
\hline
\end{tabular}


\begin{tabular}{*5{c}}
\multicolumn{5}{c}{\makebox[0pt]{This is a piece of text. The longer it is, the longer the last column.}} \\ 
1 & 2 & 3 & 4 & 5 \\
\hline
\end{tabular}


\begin{tabular*}{\textwidth}{@{\extracolsep{\textwidth minus\textwidth}}*5{c}@{}}
\multicolumn{5}{c}{This is a piece of text. The longer it is, the longer the last column.} \\ 
1 & 2 & 3 & 4 & 5 \\
\hline
\end{tabular*}


\begin{tabularx}{\textwidth}{*{5}{>{\centering\arraybackslash}X}}
\multicolumn{5}{c}{This is a piece of text. The longer it is, the longer the last column.} \\ 
1 & 2 & 3 & 4 & 5 \\
\hline
\end{tabularx}


\end{document}

Related Question