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I'm trying to do something similar to "Using the same figure twice with no new number", but with the algorithm2e package.
Therefore I wrote the following code.

\newcommand{\repeatAlgoCaption}[2]{%
    \renewcommand{\thealgocf}{\ref{#1}}% modify the displayed label
    \captionsetup{list=no}% not displayed in the list of algorithms
    \caption{#2 (repeated from page~\pageref{#1})}% page reference of the original algorithm
    \addtocounter{algocf}{-1}% the next figure after the repeat gets the right number
}

Using this code with hyperref produces the following error

! Argument of \reserved@a has an extra }.
<inserted text>
              \par

I have no clue how to get this to work, any suggestion is appreciated.

This is my working MWE (without hyperref)

\documentclass{article}
    
\usepackage{caption}
\usepackage{algorithm2e}
    
% from https://tex.stackexchange.com/questions/200211/
\newcommand{\repeatAlgoCaption}[2]{%
    \renewcommand{\thealgocf}{\ref{#1}}% modify the displayed label
    \captionsetup{list=no}% not displayed in the list of algorithms
    \caption{#2 (repeated from page~\pageref{#1})}% page reference of the repeted algorithm
    \addtocounter{algocf}{-1}% the next figure after the repeat gets the right number
}
    
% \usepackage{hyperref}% The one guilty
    
% arara: pdflatex
% arara: pdflatex
\begin{document}
    
\begin{algorithm}[H]
\caption{my caption}\label{alg:mylabel}
\end{algorithm}
    
\begin{algorithm}[H]
\caption{my other caption}
\end{algorithm}
    
\begin{algorithm}[H]
\repeatAlgoCaption{alg:mylabel}{my caption}
\end{algorithm}
    
\begin{algorithm}[H]
\caption{my other caption}
\end{algorithm}
    
\end{document}

The output is

correct ouput

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1 Answer 1

Reset to default
1

One could save the contents of \thealgoc (using an extra macro) instead of using \ref (or \ref*), for example:

\documentclass{article}

\usepackage{caption}
\usepackage{algorithm2e}

\makeatletter
\newcommand\saveAlgoCounter[1]{%
    \expandafter\xdef\csname saveAlgoCounter@#1\endcsname{\thealgocf}}% save \thealgocf
\newcommand{\repeatAlgoCaption}[2]{%
    \expandafter\let\expandafter\thealgocf\csname saveAlgoCounter@#1\endcsname% use saved \thealgocf
    \captionsetup{list=no}%
    \caption{#2 (repeated from page~\pageref{#1})}% page reference of the repeted algorithm
    \addtocounter{algocf}{-1}% the next figure after the repeat gets the right number
}
\makeatother

\usepackage[hypertexnames=false]{hyperref}% The one guilty
% "hypertexnames=false" prevents the warning "destination with the same identifier (name{algocf.1}) has been already used, duplicate ignored"

% arara: pdflatex
% arara: pdflatex
\begin{document}

\begin{algorithm}[H]
\caption{my caption}\label{alg:mylabel}
\saveAlgoCounter{alg:mylabel}
\end{algorithm}

\begin{algorithm}[H]
\caption{my other caption}
\end{algorithm}

\begin{algorithm}[H]
\repeatAlgoCaption{alg:mylabel}{my caption}
\end{algorithm}

\begin{algorithm}[H]
\caption{my other caption}
\end{algorithm}

\end{document}
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2
  • May I ask you why \ref or \ref* don't work? Commented Mar 28, 2021 at 10:33
  • 1
    \ref uses the aux file to get the information and therefore contains code which isn't easy to handle, at least not for me who isn't a TeX freak. Furthermore things like \ref do not deliver the needed information on the 1st LaTeX run. Both are reasons - at least for me - to store and restore \thealgoc on my own. (Luckily we don't need back references here.) So in short: I have no clue why \ref or \ref* does not work here but since I'm not a TeX freak I guess I would not even understand the explanation. But I'm looking forward to a better solution for this problem than mine. Commented Mar 28, 2021 at 12:27

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