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改变节点厚度会导致子图折叠

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改变节点厚度会导致子图折叠

我有以下代码生成彩色子图：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{graphs,graphs.standard}

\usepackage{etoolbox}

\begin{document}

\begin{tikzpicture}[transform shape]
  \foreach \x in {1,...,6}{%
    \pgfmathparse{(\x-1)*360/6 + 90}
    \ifboolexpr{test {\ifnumcomp{\x}{=}{1}}}
    {\node[draw=cyan, circle, inner sep=0.15cm] (N-\x) at (\pgfmathresult:2cm) {$X_{\x}$};}
    {\node[draw, circle,inner sep=0.15cm] (N-\x) at (\pgfmathresult:2cm) {$X_{\x}$};}
  } 
  \foreach \x [count=\xi from 1] in {1,...,6}{%
    \foreach \y in {\x,...,6}{%
      \ifboolexpr{test {\ifnumcomp{\x}{=}{1}}}
      {\path (N-\x) edge[thick, draw=cyan,-] (N-\y);}
      {\path (N-\x) edge[thick, -] (N-\y);} 
  }
}
\end{tikzpicture}

\end{document}

如果我改变：

    {\node[draw=cyan, circle, inner sep=0.15cm] (N-\x) at (\pgfmathresult:2cm) {$X_{\x}$};}
    {\node[draw, circle,inner sep=0.15cm] (N-\x) at (\pgfmathresult:2cm) {$X_{\x}$};}

到：

    {\node[draw=cyan, thick, circle, inner sep=0.15cm] (N-\x) at (\pgfmathresult:2cm) {$X_{\x}$};}
    {\node[draw, thick, circle,inner sep=0.15cm] (N-\x) at (\pgfmathresult:2cm) {$X_{\x}$};}

该图折叠如下： https://i.snipboard.io/95lKAD.jpg

会发生什么事？

答案1

欢迎！这是因为\pgfmathresult覆盖了设置线宽的例程。（在这种情况下，它是由 引起的thick，其定义为

 \tikzset{thick/.style={line width=0.8pt}}%

其中线宽调用\pgfsetlinewidth，其中包含

\pgfmathsetlength\pgflinewidth{#1}

其中\pgfmathsetlength包含一个\pgfmathparse，它将覆盖 的“外部”值\pgfmathresult。）这是一个众所周知的问题，解决这个问题最安全的方法可能是不要使用\pgfmathparse后面跟着其他解析表达式的东西。此外，你不需要预解析这些表达式，Ti钾无论如何，Z 都会解析它们。（另外，您不使用任何库，而是可以使用\ifnum它们来代替etoolbox。）这是解决问题的众多方法之一。

\documentclass{article}
\usepackage{tikz}
\begin{document}

\begin{tikzpicture}[transform shape]
  \foreach \x in {1,...,6}{%
    \ifnum\x=1
     \node[draw=cyan, thick,circle, inner sep=0.15cm] (N-\x) at ({(\x-1)*360/6 + 90}:2cm) {$X_{\x}$};
    \else
     \node[draw,thick, circle,inner sep=0.15cm] (N-\x) at ({(\x-1)*360/6 + 90}:2cm) {$X_{\x}$};
    \fi
  } 
  \foreach \x  in {1,...,6}{%
    \foreach \y in {\x,...,6}{%
      \ifnum\x=1
       \path (N-\x) edge[thick, draw=cyan,-] (N-\y);
      \else 
       \path (N-\x) edge[thick, -] (N-\y);
      \fi
  }
}
\end{tikzpicture}
\end{document}

在此处输入图片描述

您还可以使用\pgfmathsetmacro将计算结果存储在不会被覆盖的宏中，或者使用evaluate附带的键foreach，这只是一些存在的替代方案。以下是此类的较短版本。

\documentclass{article}
\usepackage{tikz}
\begin{document}

\begin{tikzpicture}
  \foreach \x [evaluate=\x as \myangle using {(\x-1)*360/6 + 90}]in {1,...,6}{%
    \ifnum\x=1
     \node[draw=cyan, thick,circle, inner sep=0.15cm] (N-\x) at (\myangle:2cm) {$X_{\x}$};
    \else
     \node[draw,thick, circle,inner sep=0.15cm] (N-\x) at (\myangle:2cm) {$X_{\x}$};
    \fi
    \ifnum\x>1
    \foreach \y in {1,...,\x}{%
      \ifnum\y=1
       \path (N-\x) edge[thick, draw=cyan,-] (N-\y);
      \else 
       \path (N-\x) edge[thick, -] (N-\y);
      \fi}
    \fi  
}
\end{tikzpicture}
\end{document}

如果你挖掘得足够长，你可以使它变得更短，但也许会以牺牲可读性为代价。

有一件事可能更重要一些：除了[count=\xi from 1]这里没有目的之外，我不会使用\xi宏，如果你想在循环中打印相应的希腊字母，你会感到惊讶。

附录：某些版本可进行任意突出显示。

\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[declare function={ihighlight=3;}]
  \foreach \x [evaluate=\x as \myangle using {(\x-1)*360/6 + 90}]in {1,...,6}{%
    \pgfmathtruncatemacro{\itest}{\x==ihighlight}
    \ifnum\itest=1
     \node[draw=cyan, thick,circle, inner sep=0.15cm] (N-\x) at (\myangle:2cm) {$X_{\x}$};
    \else
     \node[draw,thick, circle,inner sep=0.15cm] (N-\x) at (\myangle:2cm) {$X_{\x}$};
    \fi
    \ifnum\x>1
    \foreach \y in {1,...,\x}{%
      \pgfmathtruncatemacro{\itest}{\x==ihighlight || \y==ihighlight}
      \ifnum\itest=1
       \path (N-\x) edge[thick, draw=cyan,-] (N-\y);
      \else 
       \path (N-\x) edge[thick, -] (N-\y);
      \fi}
    \fi  
}
\end{tikzpicture}
\end{document}

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