Tikz 链节点循环到节点的开始

Question

我正在尝试在链接列表中创建一个节点并让它指向自身。

\begin{tikzpicture}[list/.style={rectangle split, rectangle split parts=2,
draw, rectangle split horizontal}, >=stealth, start chain]
  \node[list,on chain] (A) {1};
  \coordinate[above = 0.3 of A] (aa);

  \draw[*-] let \p1 = (A.two), \p2 = (A.center) in (\x1,\y2) -- (A.east);

  \draw [-] (A.east) to[bend right=90] node[auto] {} (aa);
  \draw [->] (aa) to[bend right=90] node[auto] {} (A.west);
\end{tikzpicture}

结果如下图所示。

但我希望它能像下面这样更漂亮。单箭头就能直击目标。

Answer 1

通过路径，您可以直接用和curve to传递绝对角度。inout

\draw (A) to[out=0, in=0] ([shift=(up:.3)] A.north) to[out=180, in=180] (A);

虽然我会使用不同的路径，并*在其中添加箭头。在to path样式中使用它可以轻松重复使用并用作边缘。

需要用到材料\pgfextra来将边缘上的节点运送到节点上方的水平部分。

代码

\documentclass[tikz,convert=false]{standalone}
\usetikzlibrary{arrows,shapes.multipart}
\makeatletter
\tikzset{
  dotloop above/.style={
    *->,
    looseness=#1,
    to path={
      \pgfextra{%
        \let\myTikZtostart\tikztostart
        \let\myTikZ@tonodes\tikz@tonodes
      }
      (\myTikZtostart.two |- \myTikZtostart.east) -- (\myTikZtostart.east) 
      to[out=0,in=0]  ([shift=(up:+.3cm)] \myTikZtostart.north east) -- ([shift=(up:+.3cm)] \myTikZtostart.north west)
      {\pgfextra{\tikz@node@is@a@labeltrue}\myTikZ@tonodes} to[out=180, in=180] (\myTikZtostart.west)
    }
  },
  dotloop above/.default=1.5,
}
\makeatother
\begin{document}
\begin{tikzpicture}[
  list/.style={
    rectangle split,
    rectangle split parts=2,
    draw,
    rectangle split horizontal},
  >=stealth,
  auto=right]

  \node[list] (A) {1};

  \path (A) edge[dotloop above] node {node} (A);
\end{tikzpicture}
\end{document}

输出

Answer 2

两个选项：第一个使用语法controls，另一个使用修饰ellipse（我抑制了它，chain因为它对于示例来说不是必需的）：

\documentclass{article}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{shapes.multipart,arrows,decorations.markings}

\begin{document}

\begin{tikzpicture}[
list/.style={
  rectangle split,
  rectangle split parts=2,
  draw,
  rectangle split horizontal}, 
>=stealth
]
\node[list] (A) {1};
\draw[*-] (A.two|-A.center) -- (A.east);
\draw [->] (A.east) -- +(5pt,0) .. controls +(70:1) and +(100:1) ..   
  ([xshift=-5pt]A.west) -- (A.west);
\end{tikzpicture}
\vspace{1cm}
\begin{tikzpicture}[
list/.style={
  rectangle split,
  rectangle split parts=2,
  draw,
  rectangle split horizontal}, 
>=stealth
]
\draw[decoration={
    markings,
    mark=at position 0.62 with {\arrow{>}}},postaction=decorate] 
  ([yshift=8pt]A.center) ellipse [x radius=19pt,y radius=10pt];
\node[list,fill=white] (A) {1};
\draw[*-] (A.two|-A.center) -- (A.east);
\end{tikzpicture}

\end{document}