在标题中打印子图范围

Question

考虑以下 MWE：

\documentclass{article}

\usepackage[demo]{graphicx}
\usepackage{subcaption}
\usepackage{caption}
\begin{document}
\begin{figure}

\subcaptionbox{\label{fig:img1}}{%
 \includegraphics[width=0.5\columnwidth]{image.jpg}}%
\subcaptionbox{\label{fig:img2}}{%
 \includegraphics[width=0.5\columnwidth]{image.jpg}%
}
\caption{Caption}
\end{figure}

\end{document}

这一切都很好，但我希望实现的是主标题自动为我提供子图的范围（不用管这里的子标题）。所以在Figure 1这种情况下，我希望 LaTeX 打印Figure 1a–b（如果有更多子图，则进行相应调整）。

到目前为止，我已经用 手动重新定义了标题\renewcommand{\thefigure}{\arabic{figure}a--b}，但我希望能够自动完成。

Answer 1

\subcaptionbox可以通过以下方法解决此问题：

\documentclass{article}

\usepackage{graphicx}
\usepackage{subcaption}
\usepackage{caption}

\usepackage{etoolbox}
\newcommand*\MySubcaptionFirst{}
\newcommand*\MySubcaptionLast{}
\makeatletter
\newcommand*\MySubcaptionRange
  {%
    \MySubcaptionFirst
    \ifx\MySubcaptionLast\@empty
    \else
      --\MySubcaptionLast
    \fi
  }
\newcommand*\SubCaptionBoxPatch
  {%
    \ifx\MySubcaptionFirst\@empty
      \expandafter\def\csname the\@captype\endcsname
        {\arabic{\@captype}\MySubcaptionRange}%
      \edef\MySubcaptionFirst{\csname thesub\@captype\endcsname}%
    \else
      \edef\MySubcaptionLast{\csname thesub\@captype\endcsname}%
    \fi
  }
\apptocmd \caption@iiibox 
  {\SubCaptionBoxPatch} 
  {}
  {\GenericError{}{Patching failed}{}{}}
\makeatother
\begin{document}
\begin{figure}
  \subcaptionbox{\label{fig:img1}}
    {\includegraphics[width=0.45\columnwidth]{example-image-duck}}
  \subcaptionbox{\label{fig:img2}}
    {\includegraphics[width=0.45\columnwidth]{example-image-duck}}
  \subcaptionbox{\label{fig:img3}}
    {\includegraphics[width=0.45\columnwidth]{example-image-duck}}
  \caption{Caption}
\end{figure}

\begin{figure}
  \subcaptionbox{\label{fig:img1}}
    {\includegraphics[width=0.5\columnwidth]{example-image-duck}}%
  \subcaptionbox{\label{fig:img3}}
    {\includegraphics[width=0.5\columnwidth]{example-image-duck}}%
  \caption{Caption}
\end{figure}
\begin{figure}
  \subcaptionbox{\label{fig:img3}}
    {\includegraphics[width=0.5\columnwidth]{example-image-duck}}%
  \caption{Caption}
\end{figure}
\begin{figure}
  \caption{Caption}
\end{figure}
\end{document}

Answer 2

这里有一个使用 cleveref 来格式化标签范围的选项。您只需指定分配给子图的第一个和最后一个标签。

\documentclass{article}

\usepackage{graphicx}
\usepackage{subcaption}
\usepackage{caption}
\usepackage{cleveref}

\crefrangeformat{figure}{#3#1#4--#5\crefstripprefix{#1}{#2}#6}
\newcommand{\subfigurecaption}[3]{%
    \begingroup
        \renewcommand{\thefigure}{\crefrange{#1}{#2}}
        \caption{#3}
    \endgroup
}

\begin{document}
\begin{figure}

\subcaptionbox{\label{fig:img1}}{%
 \includegraphics[width=0.5\columnwidth]{example-image-duck}}%
\subcaptionbox{\label{fig:img2}}{%
 \includegraphics[width=0.5\columnwidth]{example-image-duck}%
}
\subfigurecaption{fig:img1}{fig:img2}{Caption}
\end{figure}

\begin{figure}

\subcaptionbox{\label{fig:img3}}{%
 \includegraphics[width=0.3\columnwidth]{example-image-duck}}%
\subcaptionbox{}{%
 \includegraphics[width=0.3\columnwidth]{example-image-duck}}%
\subcaptionbox{\label{fig:img4}}{%
 \includegraphics[width=0.3\columnwidth]{example-image-duck}%
}
\subfigurecaption{fig:img3}{fig:img4}{Caption}
\end{figure}
\end{document}