Want to add a string left of "Figure" in caption

Question

Ok I need to redefine caption and probably some other things to do something like

\caption{code}{caption string}

So when a figure is made

(code) Figure #: caption string

comes out code will be a letter and can be colored differently (e.g. red or blue) for example a red R (no quotes on the R) or blue D (no quotes on the D) where Figure and the caption string are in black.

e.g.

\caption{\textcolor{red}{R}}{use this caption string}

would come out something like

(R) Figure 1: use this caption string

And I need it to work for tables too.

Can anyone help me with the renew command for this?

Answer 1

You can patch the figurename:

\renewcommand{\figurename}{\textcolor{red}{(R)}\,Figure}

If you put this in the preamble, the change applies to all figures. Instead, put it inside the figure environment to make it local.

Code:

\documentclass{article}
\usepackage{xcolor}
\usepackage{graphicx}
\begin{document}
\begin{figure}[htb]
\renewcommand{\figurename}{\textcolor{red}{(R)}\,Figure}
\includegraphics[width=\textwidth]{example-image-a}
\caption{This is a figure}
\end{figure}
\begin{figure}[htb]
%\renewcommand{\figurename}{\textcolor{red}{(R)}\,Figure}
\includegraphics[width=\textwidth]{example-image-a}
\caption{This is a figure}
\end{figure}

\end{document}

For tables, do something similar:

\renewcommand{\tablename}{\textcolor{red}{(R)}\,Table}

Answer 2

Here's an option defining a new caption format using \DeclareCaptionFormat from the caption package; this format is used, via \captionsetup, for a new command \ccaption with the following syntax:

\ccaption[<caption for the list>]{<color>}{<character>}{<caption for the document>}

Here's the code:

\documentclass{article}
\usepackage{xcolor}
\usepackage{caption}

\newcommand\ccolor{black}
\newcommand\cchar{R}

\DeclareCaptionFormat{myformat}{\textcolor{\ccolor}{(\cchar)}~#1#2#3}

\newcommand\ccaption[4][]{%
  \renewcommand\ccolor{#2}
  \renewcommand\cchar{#3}
  \captionsetup{format=myformat}
  \caption[#1]{#4}}

\begin{document}
\listoftables

\begin{figure}[!ht]
\caption{A regular caption}
\end{figure}

\begin{figure}[!ht]
\ccaption{red}{D}{A modified caption for a figure}
\end{figure}

\begin{table}[!ht]
\ccaption[Caption for the list]{blue}{R}{A modified caption for a table}
\end{table}

\begin{table}[!ht]
\ccaption{cyan}{E}{Another modified caption for a table}
\end{table}

\end{document}

The use of [!ht] is just for this example; I am not recommending using this.

Answer 3

This solution doesn't rely on the caption package and is able to dynamically change the appearence of \figurename and \tablename.
(As it uses the internal \@captype (that expands in our cases to figure or table), it should work in other environments, that define a caption, too).

Explanation

letltxmacro: saving the definition of \caption

At first we backup the original definition of \caption[<list>]{<caption>} to \ocaption.

xparse: defining the new \caption

Then we declare the new command: \caption[<color>]{<pre>}[<list>]{<caption>}

1. <color> _{^{(optional, default black)}}: The color in which (<pre>) appears. If <pre> is empty, <color> is simply ignored.
2. <pre>: The prefix that appears in <color> and surrounded by (). If it's empty than the () are omitted.
3. <list> _^(optional): behaves like the original optional argument of \caption.
4. <caption>

etoolbox: (code) goes where?

As egreg pointed out in the commands, because \figurename, \tablename and so on will most likely not use a parameter, there's no need to use \pretocmd.
These patch-lines can even be shorten further when we use \cspreto{\@captype name}{…} instead of \expandafter\preto\csname\@captype name\endcsname{…}.

\ocaption: the caption

The last line of the new \caption command uses the old \caption definition (now saved in \ocaption) to finally deal with the caption.

Notes

• I used \llap to typeset (code) so that it doesn't change the horizontal alignment of the caption (compare captions 1 and 2). If you don't want this behavior, see code comments.

• You still can use \ocaption[<list>]{<caption>} to use the original definition. But you can use the new \caption{}[<list>]{<caption>} with an empty second argument to get the same behavior.

• You may define your own command if you need to use (R) or (D) repeatedly:

  \newcommand{\Rcaption}[2][]{%
    \ifx\\#1\\%
      \caption[red]R{#2}%
    \else%
      \caption[red]R[#1]{#2}%
    \fi%
  }
  

• If you rather rarely will use the new \caption command and often use your own \Rcaption commands, you don't have to redefine \caption and instead define an improved \newcaption. See section “Code (unchanged \caption)”!

Code (changed \caption)

\documentclass{article}
\usepackage{xcolor}
\usepackage{xparse}
\usepackage{letltxmacro}
\usepackage{etoolbox}
\makeatletter
\LetLtxMacro{\ocaption}{\caption}
\DeclareDocumentCommand{\caption}{O{black}mO{}m}{% #1 = color for added #2
                                                 % #2 = text to appear in front of Figure, Table, ...
                                                 % #3 = caption for list
                                                 % #4 = caption
  {% keep changes local!
  \ifx\\#2\\\else%
    \cspreto{\@captype name}{\ifvmode\textcolor{#1}{(#2)}~\else\llap{\textcolor{#1}{(#2)}~}\fi}{}{}% (with \llap)
%    \cspreto{\@captype name}{\textcolor{#1}{(#2)}~}{}{}% (without \llap)
  \fi%
  \ifx\\#3\\\ocaption{#4}\else\ocaption[#3]{#4}\fi%
  }%
}
\makeatother
\newcommand{\Rcaption}[2][]{%
  \ifx\\#1\\%
    \caption[red]R{#2}%
  \else%
    \caption[red]R[#1]{#2}%
  \fi%
}
\newcommand{\Dcaption}[2][]{%
  \ifx\\#1\\%
    \caption[blue]D{#2}%
  \else%
    \caption[blue]D[#1]{#2}%
  \fi%
}
\begin{document}
\listoffigures
\listoftables

\hrulefill
\begin{figure}[!ht]
\Rcaption{Caption 1}
\end{figure}
\begin{figure}[!ht]
\caption{}{Caption 2}
\end{figure}
\begin{figure}[!ht]
\Dcaption[Caption 3]{Caption 3 but longer}
\end{figure}

\hrulefill
\begin{table}[!ht]
\Rcaption{Caption 4}
\end{table}
\begin{table}[!ht]
\caption[green]{A}{Caption 5}
\end{table}
\begin{table}[!ht]
\Dcaption[Caption 6 \textcolor{blue}{(D)}]{Caption 6 --- but much more longer so that it spans over one line. You can see now, that \textcolor{blue}{(D)} does not appear in the margin.}
\end{table}

Sed ut perspiciatis, unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam eaque ipsa, quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt, explicabo.
\end{document}

Code (unchanged \caption)

\documentclass{article}
\usepackage{xcolor}
\usepackage{xparse}
\usepackage{etoolbox}
\makeatletter
\DeclareDocumentCommand{\newcaption}{O{black}mO{}m}{% #1 = color for added #2
                                                    % #2 = text to appear in front of Figure, Table, ...
                                                    % #3 = caption for list
                                                    % #4 = caption
  {% keep changes local!
  \ifx\\#2\\\else%
    \cspreto{\@captype name}{\ifvmode\textcolor{#1}{(#2)}~\else\llap{\textcolor{#1}{(#2)}~}\fi}{}{}% (with \llap)
%    \cspreto{\@captype name}{\textcolor{#1}{(#2)}~}{}{}% (without \llap)
  \fi%
  \ifx\\#3\\\caption{#4}\else\caption[#3]{#4}\fi%
  }%
}
\makeatother
\newcommand{\Rcaption}[2][]{%
  \ifx\\#1\\%
    \newcaption[red]R{#2}%
  \else%
    \newcaption[red]R[#1]{#2}%
  \fi%
}
\newcommand{\Dcaption}[2][]{%
  \ifx\\#1\\%
    \newcaption[blue]D{#2}%
  \else%
    \newcaption[blue]D[#1]{#2}%
  \fi%
}
\begin{document}
\listoffigures
\listoftables

\hrulefill
\begin{figure}[!ht]
\Rcaption{Caption 1}
\end{figure}
\begin{figure}[!ht]
\caption{Caption 2}
\end{figure}
\begin{figure}[!ht]
\Dcaption[Caption 3]{Caption 3 but longer}
\end{figure}

\hrulefill
\begin{table}[!ht]
\Rcaption{Caption 4}
\end{table}
\begin{table}[!ht]
\newcaption[green]{A}{Caption 5}
\end{table}
\begin{table}[!ht]
\Dcaption[Caption 6 \textcolor{blue}{(D)}]{Caption 6 --- but much more longer so that it spans over one line. You can see now, that \textcolor{blue}{(D)} does not appear in the margin.}
\end{table}

Sed ut perspiciatis, unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam eaque ipsa, quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt, explicabo.
\end{document}

Output (both cases)