Beamer enumerate labels with subscript numbers - TeX

samcarter replying to user 3.14159

Oh, that is really interesting! I should probably go and reserve `beamerx` and `xbeamer` on github :)

user 3.14159 replying to samcarter

This is a shabby, rusty proof-of-principle code that shows that *in principle* one could make some changes. Basically one would have to scan the argument before processing. Here I scan for an `=`, not claiming that this is a good choice.  
```  
\documentclass{beamer}
\pgfkeys{/beamer/.cd,enumerate/.cd,
keys/.code={\pgfkeys{/beamer/enumerate/.cd,#1}}}

\newcommand\pft[1]{{[PFT$_{#1}$]}}
\pgfkeys{/beamer/enumerate/pft/.code={
\setbeamertemplate{enumerate item}{
  \hbox{%
    \usebeamercolor[bg]{item projected}%
    \pft{\theenumi}
  }%
}}}
\makeatletter
\def\beamer@@@enum@[#1]{% 
\expandafter\pgfutil@in@\expandafter=\expandafter{#1}%
\ifpgfutil@in@%
\pgfkeys{/beamer/enumerate/keys/.try={#1}}% 
\ifpgfkeyssuccess%
\else%
\typeout{Key #1 unknown.}%
\fi
\beamer@enum@
\else%partly copied from enumerate.sty
  \@enLab{}\let\@enThe\@enQmark
  \@enloop#1\@enum@
  \ifx\@enThe\@enQmark\@warning{The counter will not be printed.%
    ^^J\space\@spaces\@spaces\@spaces The label is: \the\@enLab}\fi
  \def\insertenumlabel{\the\@enLab}
  \def\beamer@enumtempl{enumerate mini template}%
  \expandafter\let\csname the\@enumctr\endcsname\@enThe
  \csname c@\@enumctr\endcsname7
  \beamer@enum@
\fi
}  
\makeatother

\begin{document}

\begin{frame}[t]
\frametitle{title}

\begin{enumerate}[{[SR$_\bgroup1\egroup$]}]
\item First enumerate
\item Second enumerate
\end{enumerate}

\begin{enumerate}[keys=pft]
\item First enumerate
\item Second enumerate
\end{enumerate}

\end{frame}  
\end{document}   
```

user 3.14159 replying to samcarter

Nowadays one has to be careful with "starting over from scratch", but thanks for taking care of this!

samcarter replying to user 3.14159

> whether or not beamer is getting further developed.  
  
I can't speak for the other people and ducks involved, but from my side, I add smaller things that hopefully don't break backward compatibility and otherwise try to prevent it from crumbling. In the long run starting over from scratch would probably the better approach.

user 3.14159 replying to samcarter

Yes, sure. What I wanted to say with "historical" is that `beamer` predates Ti*k*Z,, and these almost magical tricks appear to have been explored later than the time at which `beamer` was written. This raises the question whether or not beamer is getting further developed.

samcarter replying to user 3.14159

> not prevent us  
  
no it does not, but the code also not appears magically :)

user 3.14159 replying to samcarter

Hmmh, this would not prevent us from installing proper pgf keys in the optional argument. Similarly to the fact that `\draw[red]...` works, i.e. Ti*k*Z figures out that what is really meant is `\draw[color=red]....` one could teach enumerate to figure out that an unknown option is something that is to be interpreted just like the optional argument of an `enumerate` package `enumerate` option.

samcarter replying to user 3.14159

The "historical" reason is that this is based on the `enumerate` package syntax

user 3.14159 replying to JeT

I am so sorry! :smile_cat:

user 3.14159 replying to samcarter

Yes, it looks good. I am wondering, though, why the arguably more powerful styles from pgf did not make it there. Most likely this has historical reasons. Yet, at times, I am wondering if one could teach beamer the pgf keys in full glory. Something like `\begin{enumerate}[pft,overlays={<+->}]...` or even `\begin{enumerate}[pft,<+->]...`.

JeT replying to user 3.14159

You drove me nuts with your keys :) but I managed to parameter pretty much all all my big project with them !

samcarter replying to user 3.14159

```  
\documentclass{beamer}

\newcommand\pft[1]{{[SR$_{#1}$]}}

\defbeamertemplate{enumerate item}{pft}{
  \hbox{%
    \usebeamercolor[bg]{item projected}%
    \pft{\theenumi}
  }%
}



\begin{document}

\begin{frame}[t]
\frametitle{title}

\begin{enumerate}
\item First enumerate
\item Second enumerate
\end{enumerate}

{
\setbeamertemplate{enumerate item}[pft]
\begin{enumerate}
\item First enumerate
\item Second enumerate
\end{enumerate}
}

\begin{enumerate}
\item First enumerate
\item Second enumerate
\end{enumerate}
\end{frame}  
\end{document}   
```

user 3.14159 replying to samcarter

Looks good! But is it possible to activate this template with a key such that one defines it and the user only has to say `\begin{enumerate}[pft]...` to locally activate it for one enumerate?

samcarter replying to JeT

(for more levels also modify `enumerate subitem`  and `enumerate subsubitem`)

samcarter replying to JeT

Have fun :)

JeT replying to samcarter

I steal this one !

samcarter

```  
\documentclass{beamer}

\newcommand\pft[1]{{[SR$_{#1}$]}}

\setbeamertemplate{enumerate item}{
  \hbox{%
    \usebeamercolor[bg]{item projected}%
    \pft{\theenumi}
  }%
}

\begin{document}

\begin{frame}[t]
\frametitle{title}

\begin{enumerate}
\item First enumerate
\item Second enumerate
\end{enumerate}

\end{frame}  
\end{document}    
```

samcarter replying to user 3.14159

A more general approach could be to set the enumerate item template

user 3.14159

@samcarter, re: [your answer](#a1680), I am a bit curious on how one can employ arbitrary macros. One obvious possibility is  
```  
\documentclass[xcolor={rgb}]{beamer}
\beamertemplatenavigationsymbolsempty
\setbeamersize{text margin left=10mm,text margin right=5mm} 
\begin{document}

\newcommand\pft[1]{{[SR$_{#1}$]}}

\begin{frame}[t]
\frametitle{title}
\addtolength{\leftmargini}{-0.7cm}
\setbeamertemplate{itemize items}[circle]
\begin{itemize}[<+->]
\setlength\itemsep{5pt plus 1fill}
\item First line of text:
\addtolength{\leftmarginii}{0.2cm}
\begin{enumerate}[{\expandafter\pft1}]
\item First enumerate
\item Second enumerate
\end{enumerate}
\end{itemize}
\end{frame}  
\end{document}  
```  
but I am wondering if there is an alternative using some beamer template. Do you know of such a possibility?

topnush

it does get rid of the space on its own which is cool

samcarter replying to topnush

You need them for enumerate with more than 10 entries, otherwise it should also work without

topnush

is it the {} that gets rid of the space to the right?

topnush

b for beginning, e for end. Thanks

samcarter replying to topnush

`\bgroup` and `\egroup` is just like `{}`, but `{}` would disable the replacement of 1 with the current enumerate number so using this workaround instead

topnush

could you add something about bgroup and egroup please

1 Answer