在 tikz 中分割圆形节点

Question

我正在尝试使用 tikz 包重现附图，但很难拆分其中带有 {X,x} 的节点。有什么建议吗？

这是我目前想到的办法，但还不够好。{X,x} 节点需要旋转和分割，如图所示（颜色不重要）：

\begin{tikzpicture}
  \node [circle split,
         draw,
    line width = .05cm,
         minimum width=1cm,
         append after command={%
          let \p1=($(\tikzlastnode.east)-(\tikzlastnode.west)$) in  
              node[draw,
                   shape=semicircle,
                   rotate=180,
                   anchor=south,
                   double,
                   minimum width=\x1] at (\tikzlastnode.center)     {}}]
  {$X$
    \nodepart{lower}
    $x$
  };
\node [ellipse,draw,line width=.05cm] at (3.75,0) {$Y(x)$};
\node [circle,draw,line width=.05cm] at (1.5,3) {$L$};
\node [circle,draw,line width=.05cm] at (4,4.5) {$H$};
\draw[->, line width=.125cm] (1.1,0) -- (2.5,0);
\draw[->, line width=.125cm] (0.9,3) to [out=180,in=90]  (-.5,1);
\draw[->, line width=.125cm] (1.8,2.6) -- (3,.75);
\draw[->, line width=.125cm] (3.45,4.2) -- (2.1,3.25);
\draw[->, line width=.125cm] (4,3.9) -- (4,.85);
%\draw[help lines] (0,0) grid (8,6) ;
\end{tikzpicture}

Answer 1

semicircle为什么不使用库中的旋转形状shapes.geometric？

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric,positioning}

\tikzset{
semi/.style={
  semicircle,
  draw,
  minimum size=2em
  }
}

\begin{document}

\begin{tikzpicture}[line width=0.05cm]
\node [circle,draw] (h) {$H$};
\node [circle,draw,below left=1cm and 1.5cm of h] (l) {$L$};
\node [ellipse,draw,below=3.5cm of h] (y) {$Y(x)$};
\node[semi,left=2cm of y,shape border rotate=270] (x) {$x$};
\node[semi,left=0.3cm of x,shape border rotate=90] (X) {$X$};
\begin{scope}[line width=.125cm,shorten >= 5pt, shorten <= 5pt]
\draw[->] (x) -- (y);
\draw[->] (l) to [out=180,in=90]  (X);
\draw[->] (l) -- (y);
\draw[->] (h) -- (l);
\draw[->] (h) -- (y);
\end{scope}
%\draw[help lines] (0,0) grid (8,6) ;
\end{tikzpicture}

\end{document}

请注意，我使用positioning库来放置节点，因此您不必手动指定坐标；我还使用了scope带有shorten选项来绘制边。