Graphics, Figures & Tables ⇒ tabularx, multicolumn, and textwidth

[rspringuel]

I'm trying to create a fairly simply table using tabularx that spans the page. While this seems to be working, for the most part, there's a slight issue when I combine this with a multicolumn which spans the whole table. In particular, the multicolumn stretches off to the right further than the text in the regular columns.

MWE:

Code: Select all

\documentclass{article}
\usepackage{tabularx}

\newcolumntype{L}{>{\raggedright}X}
\newcolumntype{R}{>{\raggedleft}X}

\begin{document}
\noindent
\begin{tabularx}{\textwidth}{LR}
\hline
Some left aligned text&Some right aligned text\tabularnewline
Some more left aligned text&Some more right aligned text\tabularnewline
\multicolumn{2}{p{\textwidth}}{Some text which is supposed to span the two columns and have it's extents align with the extents of the above column.  Nothing really important to read here, just filling it out so that the text is long enough to make the point.  You can stop reading now.}\tabularnewline
\hline
\end{tabularx}
\end{document}

Anyone have any idea what might be happening and how to fix it?

[frabjous]

\textwidth would not be the same as the width of those two columns put together. Keep in mind that there is padding of \tabcolsep on each side of each cell, so the width is roughly \textwidth minus 2 * \tabcolsep. If you set it to just \textwidth it'll be too wide.

But when spanning columns with tabularx, I actually recommend using the X specifier with a modified \hsize, as discussed in section 4.3 of the tabularx documentation. \hsize would normally be width of one X-column. So for two X-columns, you want 2\hsize, but you also want to add back in the inner and outer padding for where those two columns meet, so we'll change \hsize to 2\hsize and then add 2\tabcolsep:

Code: Select all

\documentclass{article}
\usepackage{tabularx}

\newcolumntype{L}{>{\raggedright\arraybackslash}X}
\newcolumntype{R}{>{\raggedleft\arraybackslash}X}

\begin{document}
\noindent
\begin{tabularx}{\textwidth}{LR}
\hline
Some left aligned text&Some right aligned text\\
Some more left aligned text&Some more right aligned text\\
\multicolumn{2}{>{\setlength{\hsize}{2\hsize}\addtolength{\hsize}{2\tabcolsep}}X}{Some text which is supposed to span the two columns and have its extents align with the extents of the above column.  Nothing really important to read here, just filling it out so that the text is long enough to make the point.}\\
\hline
\end{tabularx}
\end{document}

span.png (7.8 KiB) Viewed 11331 times

P.S. I also recommend adding \arraybackslash into your columntypes to avoid the need for \tabularnewline rather than \\, but that's your call. I also fixed your "it's"/"its" typo for good measure. Don't hate me.

[rspringuel]

That does fix it. Thanks for the help.

I've purposely avoided the \arraybackslash in the new column types because this table is actually defined in a command and then used over and over again, potentially with multi-line arguments going into some of the cells which use '\\' to mark the line breaks.