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如何在 TikZ 中将标签圈在树叶下方

tag-icon • tag-icon tikz-pgf tikz-trees trees
如何在 TikZ 中将标签圈在树叶下方

我正在寻找如下图所示的树。但我不确定如何用虚线圈出树叶下方的标签。我目前得到的结果如下：

\begin{tikzpicture}[level distance=1.5cm,
level 1/.style={sibling distance=3.5cm},
level 2/.style={sibling distance=1cm}, ->]
\tikzstyle{every node}=[circle,draw]

\node (Root)  {$\gamma_1$}
    child {
    node {$\gamma_2$} 
    child { node[fill=black!20,label=below:$\beta1$] {$\gamma_4$} }
    child { node[fill=black!20,label=below:$\beta2$] {$\gamma_5$} }
    child { node[fill=black!20,label=below:$\beta3$] {$\gamma_6$} }
}
child {
    node[fill=red!20] {$\gamma_3$}
    child { node[fill=black!20, label=below:$\beta4$]  {$\gamma_7$} }
    child { node[fill=black!20,label=below:$\beta5$] {$\gamma_8$} }
    child { node [fill=black!20,label=below:$\beta6$]{$\gamma_9$} }
}
;
\end{tikzpicture}

谢谢您的帮助。

这就是我目前得到的

这就是我试图得到的

答案1

这是一种方法。

A

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{calc} % needed <<<<<<<<<<<<<<<<<

\begin{document}    
        
    \begin{tikzpicture}[
         level distance=1.5cm,
        level 1/.style={sibling distance=3.5cm},
        level 2/.style={sibling distance=1cm}, ->]
        \tikzstyle{every node}=[circle,draw]
                    
        \node (Root)  {$\gamma_1$}
        child {
            node {$\gamma_2$} 
            child { node[fill=black!20,label=below:$\beta_1$, name=gamma4] {$\gamma_4$} } %changed <<<<<<<<<
            child { node[fill=black!20,label=below:$\beta_2$] {$\gamma_5$} }
            child { node[fill=black!20,label=below:$\beta_3$, name=gamma6] {$\gamma_6$} }%changed <<<<<<<<<
        }
        child {
            node[fill=red!20] {$\gamma_3$}
            child { node[fill=black!20, label=below:$\beta_4$, name=gamma7]  {$\gamma_7$} }%changed <<<<<<<<<
            child { node[fill=black!20,label=below:$\beta_5$] {$\gamma_8$} }
            child { node [fill=black!20,label=below:$\beta_6$, name=gamma9]{$\gamma_9$} }%changed <<<<<<<<<
        }
        ;
        
     \draw[thick,dashed, rounded corners] ($(gamma4.north west)+(-1ex,-0.75)$) rectangle ($(gamma6.south east)+(1ex,-0.80)$);
        \draw[thick,dashed, rounded corners] ($(gamma7.north west)+(-1ex,-0.75)$) rectangle ($(gamma9.south east)+(1ex,-0.80)$);
    \end{tikzpicture}   

\end{document}

更简单的是奎伯比尔贝尔`s 评论：命名标签。

    \documentclass{article}

\usepackage{tikz}
\usetikzlibrary{fit}

\begin{document}    
        
    \begin{tikzpicture}[
         level distance=1.5cm,
        level 1/.style={sibling distance=3.5cm},
        level 2/.style={sibling distance=1cm}, ->]
        \tikzstyle{every node}=[circle,draw]
                    
        \node (Root)  {$\gamma_1$}
        child {
            node {$\gamma_2$} 
            child { node[fill=black!20,label={[name=beta1]below:$\beta_1$}] {$\gamma_4$} } %changed <<<<<<<<<
            child { node[fill=black!20,label=below:$\beta_2$] {$\gamma_5$} }
            child { node[fill=black!20,label={[name=beta3]below:$\beta_3$}] {$\gamma_6$} }%changed <<<<<<<<<
        }
        child {
            node[fill=red!20] {$\gamma_3$}
            child { node[fill=black!20, label={[name=beta4]below:$\beta_4$}]  {$\gamma_7$} }%changed <<<<<<<<<
            child { node[fill=black!20,label=below:$\beta_5$] {$\gamma_8$} }
            child { node [fill=black!20,label={[name=beta6]below:$\beta_6$}]{$\gamma_9$} }%changed <<<<<<<<<
        }
        ;
        
    \draw[dashed, rounded corners] (beta1.north west) rectangle (beta3.south east);
    \draw[dashed, rounded corners] (beta4.north west) rectangle (beta6.south east);

    \end{tikzpicture}   

\end{document}

答案2

只是为了比较，这里有一个使用 的选项forest。

在此处输入图片描述

\documentclass{article}
\usepackage{forest}
\tikzset{leaves/.style={draw, dashed, thick, rounded corners, inner sep=2pt, fit = {#1}}}

\begin{document}
\begin{forest}
for tree={
    l sep=1cm,
    if n children=0{no edge}{draw, circle, minimum size=7mm, edge={->}},  
    if level=0{s sep+=5mm}{},
    if level=2{fill=gray!30, l sep-=7mm}{}
}
[$\gamma_1$
    [$\gamma_2$
        [$\gamma_4$[$\beta_1$, name=A]][$\gamma_5$[$\beta_2$]][$\gamma_6$[$\beta_3$, name=B]]]
    [$\gamma_3$, fill=red!30
        [$\gamma_7$[$\beta_4$, name=C]][$\gamma_8$[$\beta_5$]][$\gamma_9$[$\beta_6$, name=D]]]
]
\node[leaves=(A)(B)]{};
\node[leaves=(C)(D)]{};
\end{forest}
\end{document}

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