TikZ：圆形垂直分割

Question

我想将 TikZ 节点拆分为左右两部分，就像circle split拆分为上半部分和下半部分一样，例如

\node [circle split,draw] (x){$a$ \nodepart{lower} $b$}

是否有垂直等效项，例如

\node [circle split vertical,draw] (x){$a$ \nodepart{right} $b$}？

---

这是一个分裂节点的示例水平，但我希望分割垂直的：

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{shapes,snakes}
\begin{document}

\begin{tikzpicture}
\node [circle split,draw] (z){$a$ \nodepart{lower} $b$};
\end{tikzpicture}

\end{document}

Answer 1

\documentclass{minimal}
\usepackage{graphics}
\usepackage{tikz}
\usetikzlibrary{shapes,snakes}
\begin{document}

\begin{tikzpicture}
\node [circle split,draw,rotate=90] (z){\rotatebox{-90}{$a$} \nodepart{lower} \rotatebox{-90}{$b$}};
\end{tikzpicture}

\end{document}

Answer 2

此解决方案使用 PGF 3.0.0 的pic新功能，定义一个名为的新 pic 元素，node vertically split该元素接收两个参数，即左侧和右侧部分的内容。它还为 pic 的各个部分定义名称，以便以后添加不同类型的连接，如示例中所示。

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\tikzset{
    pics/circle vertically split/.style 2 args = {
       code = {
         \node[inner sep=3pt,left] (-left) {#1};
         \node[inner sep=3pt,right] (-right) {#2};
         \path let
              \p1 = ($(-left.north west) - (-left.east)$),
              \p2 = ($(-right.west) - (-right.south east)$),
              \n1 = {max(veclen(\p1), veclen(\p2))*2}
           in node[minimum size=\n1, circle, draw] (-shape) at (0,0) {};
         \draw (-shape.north) -- (-shape.south);
       }
    }
}

\begin{document}
\begin{tikzpicture}

\draw (0,0)  pic (A) {circle vertically split={$a$}{$b$}}
      (2,2)  pic (B) {circle vertically split={Hello}{World}}
      (2,-1) pic (C) {circle vertically split={Hello}{$b$}};

\draw[->, blue]  (A-shape) -- (B-shape);
\draw[blue, dotted] (C-shape.north east) -- (B-shape.south east);
\draw[->, red]   (A-right) to[out=0,in=90] (C-right.north);

\end{tikzpicture}
\end{document}

结果：

Answer 3

PSTricks 解决方案：

\documentclass{article}

\usepackage{pstricks}

\def\size{2 }

\begin{document}

\begin{pspicture}(-\size,-\size)(\size,\size)
  \pswedge{\size}{90}{270}
  \rput(!-\size 2 div 0){\Huge $a$}
  \pswedge{\size}{270}{90}
  \rput(!\size 2 div 0){\Huge $b$}
\end{pspicture}

\end{document}