[Tex/LaTex] using standalone with algorithmicx or algorithm2e

algorithm2ealgorithmicxstandalone

I am trying to compile a standalone file containing pseudocode created with the algorithmicx package.
According to algorithmicx crashes standalone it should work with the preview option set for standalone, however it does not.
Also the mentioned vbox hack does not work.
What am I doing wrong?

The first compiler error:

! Extra }, or forgotten \endgroup.
\@endfloatbox ...pagefalse \outer@nobreak \egroup 
                                                  \color@endbox
l.13 \end{algorithm}

The (generic) pseudocode file:

\documentclass[preview]{standalone}
\usepackage{algorithm}
\usepackage{algpseudocode}

\begin{document}
\vbox{
\begin{algorithm}
  \caption{Euclid’s algorithm}\label{euclid}
  \begin{algorithmic}[1]
    \State $r\gets a\bmod b$
  \end{algorithmic}
\end{algorithm}
}
\end{document}

Thank you for your help.

Sven

UPDATE:

Using the algorithm2e package (as suggested by David Carlisle) and not using the vbox lets the pseudocode file compile without errors.

When I use \KwIn{foo} it breaks again. This in turn is fixed by using \usepackage[varwidth]{standalone}. The pseudocode file compiles without errors.

However now when I try to include the pseudocode file in my main file, I get the following compilation error in the algorithm2e.sty when compiling the main file:

! Undefined control sequence.
&lt;argument&gt; \SetAlgoLined 

l.1177 ...etcount,titlenotnumbered,lined,shortend}
                                                  %

The new pseudocode file (without ~\\ there is no line break after \KwIn{foo}):

\documentclass[varwidth]{standalone}
\usepackage[utf8]{inputenc}
\usepackage{algorithm2e}

\begin{document}
\begin{algorithm}
  ~\\
  \KwIn{foo}
  $r\gets a\bmod b$\;  
\end{algorithm}
\end{document}

The main file where pseudocode is included:

\documentclass[a4paper,10pt]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[subpreambles]{standalone}

\begin{document}
\include{pseudocode}
\end{document}

Best Answer

I've lost track a bit of the various packages but your example runs without error (with or without the \vbox) if you change

\usepackage{algorithm}

\usepackage{algorithm2e}

Related Solutions

[Tex/LaTex] How to have the algorithmicx comment symbol in algorithm2e

From the algorithm2e documentation (section 11.4 to define comments, p 35):

\SetKwComment{Comment}{<start>}{<end>} defines a macro \Comment{text comment} which writes text comment between <start> and <end>. Note that <start> or <end> can be empty.

It defines also \Comment*{side comment text} macro which allows to put comment on the same line as the code. This macro can take various option to control its behaviour:

\Comment*[r]{side comment text} put the end of line mark (; by default) and side comment text just after and right justified, then end the line. It is the default.

\Comment*[l]{side comment text} same thing but side comment text is left justified.

\Comment*[h]{side comment text} put side comment right after the text. No end of line mark is put, and line is not terminated (is up to you to put \; to end the line).

\Comment*[f]{side comment text} same as the previous one but with side comment text right justified.

Here's an example of the above:

enter image description here

\documentclass{article}
\usepackage{algorithm2e}
\SetKwComment{Comment}{$\triangleright$\ }{}
\begin{document}

\begin{algorithm}[H]
  \SetAlgoLined
  \KwData{this text}
  \KwResult{how to write algorithm with \LaTeX2e }
  initialization\;
  \While{not at end of this document}{
    read current\;
    \eIf{understand}{
      go to next section \Comment*[r]{Some comment}
      current section becomes this one\;
    }{
      go back to the beginning of current section\;
    }
  }
  \caption{How to write algorithms}
\end{algorithm}

\end{document}

If you wish to reformat the comment font, you can adjust \CommentSty. In algorithm2e this is done via (for example) \SetCommentSty{itshape} to obtain an \itshape or italics comment.

Here is a corresponding example showing the default comment style in algorithmicx, taken directly from the algorithmicx documentation:

enter image description here

\documentclass{article}
\usepackage{algorithm,algpseudocode}
\begin{document}

\begin{algorithm}
  \caption{Euclid’s algorithm}\label{euclid}
  \begin{algorithmic}[1]
    \Procedure{Euclid}{$a,b$}\Comment{The g.c.d. of a and b}
      \State $r\gets a\bmod b$
      \While{$r\not=0$}\Comment{We have the answer if r is 0}
        \State $a\gets b$
        \State $b\gets r$
        \State $r\gets a\bmod b$
      \EndWhile\label{euclidendwhile}
      \State \textbf{return} $b$\Comment{The gcd is b}
    \EndProcedure
  \end{algorithmic}
\end{algorithm}

\end{document}

[Tex/LaTex] algorithm2e style comments in algorithmicx

In answer to your commented request in the code, create something like \LineComment{<comment>}, which will set a comment right-aligned and italicized:

enter image description here

\documentclass{article}
\usepackage{algorithm}
\usepackage[noend]{algpseudocode}
\newcommand{\LineComment}[1]{\Statex \hfill\textit{#1}}

\begin{document}
\begin{algorithm}
  \begin{algorithmic}[1]
  \Procedure{Euclid}{$a,b$}\Comment{The g.c.d.\ of~$a$ and~$b$}
    \State $r \gets a \bmod b$
    \While{$r \neq 0$}\LineComment{We have the answer if~$r$ is~$0$}
      \State $a \gets b$
      \State $b \gets r$
      \State $r \gets a \bmod b$
    \EndWhile\label{euclidendwhile}
    \State \textbf{return} $b$\Comment{The g.c.d.\ is~$b$}
  \EndProcedure
  \end{algorithmic}
  \caption{Euclid’s algorithm}\label{euclid}
\end{algorithm}
\end{document}

You can format \LineComment the way you want. For example, using

\newcommand{\LineComment}[1]{\Statex \hfill/* \textit{#} */}

would wrap the line comment in /*...*/:

enter image description here

Following some guidelines in Using end-of-line delimiter in plain TeX macro, you could also use

\makeatletter
\let\fslash=/
\catcode`\/=\active
\newcommand{/}{\@ifnextchar/{\begingroup\catcode`\^^M=12 \fslash@}\fslash}
{\catcode`\^^M=12 %
 \gdef\fslash@/#1^^M{\hfill \fslash\fslash{\itshape#1}\endgroup}}
\makeatother

in order to make / active. If used in succession //, it captures the contents until the end-of-line character is reached, placing it in an italicized font:

enter image description here

\documentclass{article}
\usepackage{algorithm}
\usepackage[noend]{algpseudocode}
\newcommand{\LineComment}[1]{\Statex \hfill/* \textit{#1} */}

% https://tex.stackexchange.com/q/125549/5764
\makeatletter
\let\fslash=/
\catcode`\/=\active
\newcommand{/}{\@ifnextchar/{\begingroup\catcode`\^^M=12 \fslash@}\fslash}
{\catcode`\^^M=12 %
 \gdef\fslash@/#1^^M{\hfill \fslash\fslash{\itshape#1}\endgroup}}
\makeatother

\begin{document}
\begin{algorithm}
  \begin{algorithmic}[1]
  \Procedure{Euclid}{$a,b$}\Comment{The g.c.d.\ of~$a$ and~$b$}
    \State $r \gets a \bmod b$
    \While{$r \neq 0$}\LineComment{We have the answer if~$r$ is~$0$}
      \State $a \gets b$ // Another comment
      \State $b \gets r$
      \State $r \gets a \bmod b$
    \EndWhile\label{euclidendwhile}
    \State \textbf{return} $b$\Comment{The g.c.d.\ is~$b$}
  \EndProcedure
  \end{algorithmic}
  \caption{Euclid’s algorithm}\label{euclid}
\end{algorithm}
\end{document}

The above momentary redefinition of ^^M (the end-of-line char) could be problematic, but really depends on the circumstances. Regardless, the following might be safer:

\usepackage{etoolbox}
\makeatletter
\let\fslash=/
\catcode`\/=\active
\newcommand{/}{\@ifnextchar/{\fslash@}\fslash}
\def\fslash@/{\hfill \fslash\fslash\itshape}
\AtBeginEnvironment{algorithmic}{%
  \let\olditem\item
  \renewcommand{\item}{\upshape\olditem}
}
\makeatother

Best Answer

Related Solutions

[Tex/LaTex] How to have the algorithmicx comment symbol in algorithm2e

[Tex/LaTex] algorithm2e style comments in algorithmicx

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