Graphics, Figures & Tables ⇒ Partially colored algorithmic environment

[zaungast]

Dear all,
i've tried to partially color an algorithm defined within the algorithmic-environment. To do so, i've used a combination of \vbox and \colorbox. However, the output doesn't look like desired (see attachment), since lines 2 and 4 are not indented. Here's a short code example, illustrating the problem...

Code: Select all

\documentclass[a4paper]{article} 
\usepackage{algorithmic}
\usepackage{algorithm}
\usepackage{color}
\begin{document}

\begin{algorithm}[H]
	\caption{test algorithm}
	\begin{algorithmic}[1]
	\IF {A = B}
		\vbox{\colorbox{green}{\vbox{\IF {B = C} \STATE {C = A} \ENDIF}}}
	\ENDIF
	\end{algorithmic}
	\end{algorithm}

\end{document}

Is there any possibility to partially color an algorithm defined within the algorithmic environment?

[Stefan Kottwitz]

Hi,

welcome to the board!

Do you have the pgf package installed? I would use TikZ for that, which is a front-end for pgf - similar to this matrix example.

Stefan

[Juanjo]

Look the following code:

Code: Select all

\documentclass[a4paper]{article} 
\usepackage{algorithmic}
\usepackage{algorithm}
\usepackage{color}
\begin{document}

\begin{algorithm}[H]
   \caption{test algorithm}
   \begin{algorithmic}[1]
      \IF {A = B}  
      \hspace*{-\fboxsep}\colorbox{green}{\parbox{\linewidth}{%
      \IF {B = C} \STATE {C = A} \ENDIF}}
      \ENDIF
   \end{algorithmic}
\end{algorithm}

\end{document}

I would suggest to use the algorithmicx bundle instead of algorithmic, since it has many features that can be useful. For example,

Code: Select all

\documentclass[a4paper]{article} 
\usepackage[compatible]{algpseudocode}
\usepackage{algorithm}
\usepackage{color}
\begin{document}

\begin{algorithm}[H]
   \caption{test algorithm}
   \begin{algorithmic}[1]
      \IF {A = B}  \newline
      \hspace*{-\fboxsep}\colorbox{green}{\parbox{\linewidth}{%
      \IF {B = C} \STATE {C = A} \ENDIF}}
      \ENDIF
   \end{algorithmic}
\end{algorithm}

\end{document}

The algpseudocode package is part of algorithmicx. Above, it has been called in compatibility mode with algorithmic.

[zaungast]

The above mentioned solution by Juanjo works perfectly. Thank you very much

[betabandido]

I am also looking for a solution to highlight some lines in an algorithm. The solution posted by Juanjo works well, but it seems to fail in some cases. For instance, the following works:

Code: Select all

\begin{algorithmic}[1]
    \FORALL{$elem$ in $collection$}
        \STATE $foo(elem)$
        \hspace*{-\fboxsep}\colorbox{green}{\parbox{\linewidth}{\STATE $bar(elem)$}}
    \ENDFOR
\end{algorithmic}

If I swap the order of the statements, however, then it does not compile:

Code: Select all

\begin{algorithmic}[1]
    \FORALL{$elem$ in $collection$}
        \hspace*{-\fboxsep}\colorbox{green}{\parbox{\linewidth}{\STATE $bar(elem)$}}
        \STATE $foo(elem)$
    \ENDFOR
\end{algorithmic}

The error that I get is:

Code: Select all

! Missing \endcsname inserted.
<to be read again> 
                  \ALG@currentblock@2 
l.19 \end{frame}

Do you know what could be the reason? Is there any way to fix this error?

Thank you very much.

[localghost]

Just for information to other users for awareness of possibly already existing solutions. The question by betabandido has also been posted to {TeX} SX.

[betabandido]

Just for reference, a solution has been posted here.