Graphics, Figures & Tables ⇒ multi-element framebox in array

[Sagil]

My problem is the following: I have an array, and want to put frame boxes around elements. For a single element that's simple, e.g.

Code: Select all

\begin{array}{ccc}
0 & \fbox{1} & 1 \\
1 & 0 & 0
\end{array}

But how can you do this for multiple elements? E.g. put a box around the two adjacent '1's?

Thanks, Henning

[gmedina]

Hi Henning,

the hhline package could be helpful; take a look at the following example:

Code: Select all

\documentclass{article}
\usepackage{hhline}

\begin{document}

\[
  \begin{array}{ccc}
    \hhline{~--}0 & \multicolumn{1}{|c}{1} & \multicolumn{1}{c|}{1} \\
    \hhline{~--}1 &  0 & 0
  \end{array}
\]

\end{document}

Edit: the same result can be achieved without extra packages:

Code: Select all

\documentclass{article}

\begin{document}

\[
  \begin{array}{ccc}
    \cline{2-3}
    0 & \multicolumn{1}{|c}{1} & \multicolumn{1}{c|}{1} \\\cline{2-3}
    1 &  0 & 0
  \end{array}
\]

\end{document}

[Sagil]

Thanks, that's close but it doesn't look quite right - basically I want elements to appear as "grouped together". Consider e.g. the following code:

Code: Select all

\documentclass{article}
\usepackage{hhline}
\begin{document}
\newcommand{\lone}{\multicolumn{1}{|c}{1}}
\newcommand{\rone}{\multicolumn{1}{c|}{1}}
\newcommand{\lrone}{\multicolumn{1}{|c|}{1}}
\[
\left(
\begin{array}{cccccc}
\hhline{~~-~--}
0 & 0 & \lrone & 0 & \lone & \rone\\
\hhline{-~----}
\lrone & 0 & 0 & \lrone & 0 & \lrone\\
\hhline{-~----}
0 & 0 & \lrone & 0 & \lrone & 0\\
\hhline{~--~--}
0 & \lrone & 0 & 0 & 0 & \lrone\\
\hhline{~-~~~-}
\end{array}
\right)
\]
\[
\left(
\begin{array}{cccccc}
\hhline{~~~~--}
0 & 0 & \fbox{1} & 0 & \lone & \rone\\
\hhline{~~~~--}
\fbox{1} & 0 & 0 & \fbox{1} & 0 & \fbox{1}\\
0 & 0 & \fbox{1} & 0 & \fbox{1} & 0\\
0 & \fbox{1} & 0 & 0 & 0 & \fbox{1}\\
\end{array}
\right)
\]
\end{document}

This generates the following two matrices as output:

fboxmatrix.png (4.75 KiB) Viewed 4107 times

In the first one groupings are not very clear when '1's are close together, in the second one the box alignment is off. Any ideas?