Any way to reference a particular component of a label?

Question

I am using numberwithin to number my figures within their section. For example, I have figures 1.1, 1.2, and 1.3 in section 1 and figures 2.1 and 2.2 in section 2. What I want to do is reference just the figure number, and not the section. For example, I want a reference to read "figures 1.1-3". Is there any way to do this?

Here is what I believe to be the relevant part of the preamble in my document:

\documentclass[runningheads]{llncs}
\let\proof\relax
\let\endproof\relax
\usepackage{amsthm}
\usepackage{amssymb}
\setcounter{tocdepth}{3}
\usepackage{graphicx}
\usepackage{mathtools}
\usepackage{listings}
\usepackage{verbatim}
\usepackage{epsfig}

\usepackage[linesnumbered,ruled,vlined]{algorithm2e}
\usepackage{todonotes}
\usepackage[normalem]{ulem}
\usepackage{proof}
\usepackage{ragged2e}
\usepackage{enumitem}
\usepackage{syntax}
\usepackage{mathpartir}
\numberwithin{figure}{section}

The following is a small example with respect to the above preamble:

\begin{document}
\title{Example}
\titlerunning{Example}
\author{Me}
\maketitle
\section{First Section}
\begin{figure}[htbp]
\caption{First Figure}
\label{fig:1.1}
This is a figure.
\end{figure}
\begin{figure}[htbp]
\caption{Second Figure}
\label{fig:1.2}
This is another figure.
\end{figure}
\begin{figure}[htbp]
\caption{Third Figure}
\label{fig:1.3}
This is yet another figure.
\end{figure}
\section{Second Section}
\begin{figure}[htbp]
\caption{Fourth Figure}
\label{fig:2.1}
This is a figure in the second section.
\end{figure}
\begin{figure}[htbp]
\caption{Fifth Figure}
\label{fig:2.2}
This is another figure in the second section.
\end{figure}
\section{Conclusion}
As you can see in figures \ref{fig:1.1}-\ref{fig:1.3}, the numbering is not what I'd like. I want it to read "figures 1.1-3".
\end{document}

Answer 1

The cleveref package provides some machinery to "strip" the prefix component from an object's number when creating cross-references to ranges of objects, such as figure environments.

(In some cases such as Roman numbering, cleveref's \crefstripprefix machinery may not be enough, though, and you might need xstring's \StrCut.)

For more information on this method, see page 20 of the user guide of the cleveref package as well as postings such as Referencing a range of equations with a particular format (A.3-7) instead of (A.3)-(A.7), Crossreference in Ref Range (1a-1e) to (1a-e), and Refer to a range of subsubexamples.

\documentclass[runningheads]{llncs}
\usepackage{amsmath}   % for '\numberwithin' macro
\numberwithin{figure}{section}
\usepackage[noabbrev]{cleveref}  % see https://ctan.org/pkg/cleveref
\crefrangelabelformat{figure}{#3#1#4--#5\crefstripprefix{#1}{#2}#6}
\begin{document}
%% The following is minimalist code
\setcounter{section}{1}
\refstepcounter{figure}\label{fig:aa}
\refstepcounter{figure}\label{fig:bb}
\refstepcounter{figure}\label{fig:cc}
A cross-reference to \cref{fig:aa,fig:cc,fig:bb}. % arguments of '\cref' needen't be sorted by the user
\end {document}

---

Addendum: The solution method proposed here lets writers use \cref to create multiple cross-referencing call-outs to ranges of numbers, with the number prefix being stripped off for each range of numbers. For instance,

\documentclass[runningheads]{llncs}
\counterwithin{figure}{section}
\usepackage[noabbrev]{cleveref}  % see https://ctan.org/pkg/cleveref
\crefrangelabelformat{figure}{#3#1#4--#5\crefstripprefix{#1}{#2}#6}
\begin{document}
%% The following is minimalist code; it's not how one would normally
%% go about creating 'figure' environments, captions, and labels.
\setcounter{section}{1}
\refstepcounter{figure}\label{fig:aa} % 1.1
\refstepcounter{figure}\label{fig:bb} % 1.2
\refstepcounter{figure}\label{fig:cc} % 1.3
\stepcounter{section}
\refstepcounter{figure}\label{fig:dd} % 2.1
\refstepcounter{figure}\label{fig:ee} % 2.2
\refstepcounter{figure}\label{fig:ff} % 2.3
\refstepcounter{figure}\label{fig:gg} % 2.4
%% Now the call to \cref. Note that the arguments of \cref
%% need not be sorted in any order.
A cross-reference to \cref{fig:aa,fig:cc,fig:gg,fig:ee,fig:ff,fig:bb}. 
\end {document}

Answer 2

You can load the package refcount and define a macro \RefOnlyStuffBehindLastDot which uses refcount's \getrefbykeydefault for extracting the number from the reference before applying a tail-recursive macro which from the extracted number removes dot-delimited arguments until no dots are left:

\documentclass[runningheads]{llncs}
\usepackage{refcount}
\makeatletter
@ifdefinable\gobbletodot{\long\def\gobbletodot#1.{}}%
\newcommand\KeepOnlyStuffBehindLastDot[1]{%
  \ifcat$\detokenize\expandafter{\gobbletodot#1.}$%
  \expandafter@firstoftwo\else\expandafter@secondoftwo\fi
  {#1}{\expandafter\KeepOnlyStuffBehindLastDot\expandafter{\gobbletodot#1}}%
}%
@ifdefinable\RefOnlyStuffBehindLastDot{%
  \DeclareRobustCommand\RefOnlyStuffBehindLastDot[1]{%
    \IfRefUndefinedBabel{#1}{\refused{#1}\nfss@text{\reset@font\bfseries??}}%
                        {%
                          @ifundefined{hyperref}{@firstofone}{\hyperref[{#1}]}%
                          {%
                            \expandafter\expandafter\expandafter\KeepOnlyStuffBehindLastDot
                            \expandafter\expandafter\expandafter{\getrefbykeydefault{#1}{}{??}}%
                          }%
                        }%
  }%
}%
\makeatother
% \usepackage{hyperref}
\let\proof\relax
\let\endproof\relax
\usepackage{amsthm}
\usepackage{amssymb}
\setcounter{tocdepth}{3}
\usepackage{graphicx}
\usepackage{mathtools}
\usepackage{listings}
\usepackage{verbatim}
\usepackage{epsfig}

\usepackage[linesnumbered,ruled,vlined]{algorithm2e}
\usepackage{todonotes}
\usepackage[normalem]{ulem}
\usepackage{proof}
\usepackage{ragged2e}
\usepackage{enumitem}
\usepackage{syntax}
\usepackage{mathpartir}
\numberwithin{figure}{section}
\begin{document}
\title{Example}
\titlerunning{Example}
\author{Me}
\maketitle
\section{First Section}
\begin{figure}[htbp]
\caption{First Figure}
\label{fig:1.1}
This is a figure.
\end{figure}
\begin{figure}[htbp]
\caption{Second Figure}
\label{fig:1.2}
This is another figure.
\end{figure}
\begin{figure}[htbp]
\caption{Third Figure}
\label{fig:1.3}
This is yet another figure.
\end{figure}
\section{Second Section}
\begin{figure}[htbp]
\caption{Fourth Figure}
\label{fig:2.1}
This is a figure in the second section.
\end{figure}
\begin{figure}[htbp]
\caption{Fifth Figure}
\label{fig:2.2}
This is another figure in the second section.
\end{figure}
\section{Conclusion}
As you can see in figures \ref{fig:1.1}-\ref{fig:1.3}, the numbering is not what I'd like. I want it to read "figures 1.1-3".
As you can see in figures \ref{fig:1.1}-\RefOnlyStuffBehindLastDot{fig:1.3}, the numbering what I like. I want it to read "figures 1.1-3".
\end{document}

Answer 3

If you're not using any fancy cross-referencing packages, you can just set the reference to whatever you like before setting a \label by changing \@currentlabel:

\documentclass[runningheads]{llncs}
\usepackage{mathtools}
\numberwithin{figure}{section}
\begin{document}
\section{A section}
See Figures \ref{fig:first}--\ref{fig:final}, 
or Figures~\ref{fig:first}--\ref{fig:final-final}.
\begin{figure}
  \caption{First figure}\label{fig:first}% 1.1
  \caption{Second figure}\label{fig:second}% 1.2
  \caption{Third figure}\label{fig:third}% 1.3
  \caption{Final figure}\label{fig:final}% 1.4
  \makeatletter
  \renewcommand{@currentlabel}{\arabic{figure}}\label{fig:final-final}% 4
  \makeatother
\end{figure}
\end{document}