如何使用 `refcount` 作为章节计数器？

Question

我正在使用该refcount包将一些计数器设置为与另一个文件中的计数器相同的值.tex。另一个文件中的标签.tex随该包一起导入zref-xr。

此方法不适用于按章节编号。例如，如果外部的某个图的.tex编号为“3.2”，则会\setcounterref将“3”添加到任何计数器，并将“.2”打印到文档中。

我怎样才能仅提取后部（“2”）并将其添加到计数器中？

---

\documentclass{book}

\usepackage{filecontents}
\begin{filecontents*}{external.aux}
\newlabel{fig:external}{{3.2}{6}{external figure}{figure.3.2}{}}
\end{filecontents*}

\usepackage{refcount}
\setrefcountdefault{1}

\usepackage{zref-xr}
\zxrsetup{toltxlabel}
\zexternaldocument*[external-]{external}

\setcounter{chapter}{1}
\usepackage{hyperref}

\begin{document}

\setcounterref{figure}{external-fig:external}

\thefigure

\end{document}

Answer 1

假设所有参考编号都用句点分隔，您可以定义一个新命令来访问最后一项。

\begin{filecontents*}{external.aux}
\newlabel{fig:external}{{3.2}{6}{external figure}{figure.3.2}{}}
\newlabel{thm:x}{{2}{8}{Theorem}{theorem.2}{}}
\end{filecontents*}

\documentclass{book}
\usepackage{xparse}
\usepackage{refcount}
\usepackage{zref-xr}
\usepackage{hyperref}

\setrefcountdefault{1}
\zxrsetup{toltxlabel}
\zexternaldocument*[external-]{external}
\setcounter{chapter}{1}

\newtheorem{theorem}{Theorem}

\ExplSyntaxOn
\NewDocumentCommand{\xsetcounterref}{mm}
 {% #1 = counter, #2 = label
  \seq_set_split:Nnx \l_tmpa_seq { . } { \getrefnumber{#2} }
  \setcounter{#1}{\seq_item:Nn \l_tmpa_seq { -1 }}
 }
\cs_generate_variant:Nn \seq_set_split:Nnn { Nnx }
\ExplSyntaxOff


\begin{document}

\xsetcounterref{figure}{external-fig:external}
\thefigure

\xsetcounterref{theorem}{external-thm:x}
\thetheorem

\end{document}

的扩展值\getrefnumber{<label>}按句点分割，并检索最后一项（用\seq_item:Nn \l_tmpa_tl { -1 }）。

输出（你可以检查）将是

1.2
2

Answer 2

如果数字总是有规律⟨章节编号⟩.⟨图号⟩，不要使用\setcounterref，而是应用\setcounter组合\getrefnumber并删除点以及它前面的所有内容。

\documentclass{book}

\usepackage{filecontents}
\begin{filecontents*}{external.aux}
\newlabel{fig:external}{{3.2}{6}{external figure}{figure.3.2}{}}
\end{filecontents*}

\usepackage{refcount}[2010/12/01 v3.2] % issue warning if refcount 
                                       % older than version 3.2 is 
                                       % loaded.
\setrefcountdefault{1}

\usepackage{zref-xr}
\zxrsetup{toltxlabel}
\zexternaldocument*[external-]{external}

\setcounter{chapter}{1}
\usepackage{hyperref}

\newcommand\gobbletodot{}\long\def\gobbletodot#1.{}%

\begin{document}

% refcount manual, section 1.2 Expandable commands, states:
%   These commands that can be used in expandible contexts
%   ...
%   Since version 3.2 the expandable macros described before
%   in this section are expandable in exact two expansion steps.
%
\setcounter{figure}{\expandafter\expandafter\expandafter\gobbletodot\getrefnumber{external-fig:external}}

\thefigure

\end{document}