[OS X TeX] Square cells in tabular

[Will Robertson]

Hi all

Arno contacted me off-list about some help with this problem, and I've  
posted my solution here for all to see.

Hope it's still of help and sorry about the delay.

Regards,
Will

=== snip LaTeX document from here to end ===

\documentclass{article}
\usepackage{array,calc}

\setlength\parindent{0pt}
\setlength\parskip{1em}

\begin{document}

\section*{Square cells in a tabular}

Arno Kruse asked if it was possible to create a tabular with square  
cells. The solution involves some use of the \textsf{array} package,  
uses several \LaTeX\ length commands and the \textsf{calc} package. I  
thought that the curious might like to look at my proposal for interest  
in the solution, critique of my coding style, or (I hope!) to learn a  
little about some \LaTeX\ concepts. Please refer to the array manual  
for further explanation.

First, set every column to some width (I have used 2\,em in the current  
font). This is done with the \verb|p{...}| column specifier.

\newlength\squarecell
\setlength\squarecell{2em}

\begin{tabular}{|p{\squarecell}|p{\squarecell}|}
\hline
1 & 2 \\
\hline
3 & 4 \\
\hline
\end{tabular}

If you measure the widths of the cells, however, you'll notice that  
they are in fact \emph{larger} than 2\,em since the tabular environment  
inserts space in between each column. (This is controlled by the  
\verb|\tabsepcol| length, but I leave it alone in case other tabulars  
are being used in the document.) The intercolumn space may be  
suppressed by using the \verb|@{}| column specifier. Now each cell is  
exactly \verb|\squarecell|. I have also added a centring command to  
each cell of the tabular.

\newcolumntype{C}{@{}>{\centering\arraybackslash}p{\squarecell}@{}}
\begin{tabular}{|C|C|}
\hline
1 & 2 \\
\hline
3 & 4 \\
\hline
\end{tabular}

Now we need to set the height of each cell equal to the width. This can  
be achieved by inserting a strut (a zero width rule) of a certain  
height and a certain depth. First, I measure the height of a left  
parenthesis (`\verb|(|') to get the approximate height required to  
vertically centre the text. Then I subtract this value from the square  
cell size and divide by two to get the surrounding space.

\newlength\fontheight
\newlength\surroundcellheight
\settoheight\fontheight{(}
\setlength\surroundcellheight{(\squarecell - \fontheight)/2}
\newcolumntype{S}{ @{}
                    >{\centering\arraybackslash}
                    p{\squarecell}
                    <{\rule{0pt}{\fontheight +  
\surroundcellheight}\rule[- 
\surroundcellheight]{0pt}{\surroundcellheight}}
                    % change 0pt to 1pt to see what the rules do.
                    @{} }

\begin{tabular}{|S|S|}
\hline
1 & 2 \\
\hline
3 & 4 \\
\hline
\end{tabular}

\newpage
\section*{Example}
So now that's done, a proper example.
I define a new environment for setting these special tables called  
\texttt{squarecells}.

\newenvironment{squarecells}[1]
   {\setlength\squarecell{2em} % set the cell dimension to 2em in the  
current font
    \settoheight\fontheight{(}
    \setlength\surroundcellheight{(\squarecell - \fontheight)/2}
    \begin{tabular}{#1}}
   {\end{tabular}}

\hfill
\begin{minipage}{0.3\textwidth}
\large
\begin{squarecells}{|S|S|S|S|}
   \hline
   17 &    & 0  & 11 \\ \hline
      &    & 16 & 6  \\ \hline
      & 4  &    &    \\ \hline
   2  & 16 &    & 3  \\ \hline
\end{squarecells}
\end{minipage}
\hfill
\begin{minipage}{0.45\textwidth}
\begin{verbatim}
\begin{squarecells}{|S|S|S|S|}
   \hline
   17 &    & 0  & 11 \\ \hline
      &    & 16 & 6  \\ \hline
      & 4  &    &    \\ \hline
   2  & 16 &    & 3  \\ \hline
\end{squarecells}
\end{verbatim}
\end{minipage}
\hfill\null

\normalsize
So, in order to get this working in your own document, you'll need  
something along the lines of the following into your preamble. (I'm too  
lazy to make a proper package for it.) It doesn't work perfectly, but  
it scales reasonably well so I hope it may be of use to at least Arno.

\begin{verbatim}
\newlength\squarecell
\newlength\fontheight
\newlength\surroundcellheight

\newenvironment{squarecells}[1]
   {\setlength\squarecell{2em}
    \settoheight\fontheight{(}
    \setlength\surroundcellheight{(\squarecell - \fontheight)/2}
    \begin{tabular}{#1}}
   {\end{tabular}}
\end{verbatim}


\end{document}

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