决策树节点与 Tikz 重叠

Question

有人知道如何防止决策树的分支相互收敛吗？这是使用 Tikz 时的情况 - 我尝试调整兄弟距离等，但末端的两个分支收敛，导致最终值难以辨认。

其次，有人知道如何在两个方形“选择”兄弟之间添加虚线吗？以指示信息集。

\documentclass{article}
\usepackage{tikz}
\tikzset{
    choice/.style = {shape=rectangle, draw, align=center, color=black, fill=black, font=\normalsize},
    chance/.style = {shape=circle, draw, align=center, color=black, fill=black, font=\normalsize},
    root/.style = {choice, font=\normalsize, color=black},
    outcome/.style = {shape=rectangle, draw=white, align=center, font=\tiny, parent anchor=left},
}

\begin{figure}[H]
\centering
\begin{tikzpicture}
  [
    grow = right,
    sibling distance = 6em,
    level distance = 8em,
    edge from parent/.style = {draw, -latex},
    every node/.style = {font=\normalsize},
    sloped
  ]
\node [root] {}
    child {node [outcome, label=right:{\$30}] {}
        edge from parent node [below] {}}
    child {node [choice] {}
        child {node [chance] {}
        child {node [choice] {}
            child {node [outcome, label=right:{\$10}]{}}
            child {node[outcome, label=right:{\$100}]{}}
            edge from parent node [below] {.5}}
        child {node [choice]{}
            child {node [outcome, label=right:{\$45}]{}}
            child {node [outcome, label=right:{\$55}]{}}
            edge from parent node [above] {.5}}
        edge from parent node [below] {}}
        child {node [outcome, label=right:{\$25}]{}
            edge from parent node [above] {}}
                    edge from parent node [above] {}};
\end{tikzpicture}
\caption{Sample Decision Tree} \label{fig: Sample}
\end{figure}

Answer 1

我使用yshift选项来改变节点的位置，以避免重叠。

我给两个choice节点一些名字（a和b），并像往常一样画一条虚线。

代码：

\documentclass[tikz]{standalone}
\tikzset{
    choice/.style = {shape=rectangle, draw, align=center, color=black, fill=black, font=\normalsize},
    chance/.style = {shape=circle, draw, align=center, color=black, fill=black, font=\normalsize},
    root/.style = {choice, font=\normalsize, color=black},
    outcome/.style = {shape=rectangle, draw=white, align=center, font=\tiny, parent anchor=left},
}

\begin{document}
\begin{tikzpicture}
  [
    grow = right,
    sibling distance = 6em,
    level distance = 8em,
    edge from parent/.style = {draw, -latex},
    every node/.style = {font=\normalsize},
    sloped
  ]
\node [root] {}
    child {node [outcome, label=right:{\$30}] {}
        edge from parent node [below] {}}
    child {node [choice] {}
        child {node [chance] {}
        child {node [choice] (a) {}
            child {node [outcome, label=right:{\$10}]{}}
            child {node[yshift=-2em,outcome, label=right:{\$100}]{}}
            edge from parent node [below] {.5}}
        child {node [choice] (b) {}
            child {node [yshift=2em,outcome, label=right:{\$45}]{}}
            child {node [outcome, label=right:{\$55}]{}}
            edge from parent node [above] {.5}}
        edge from parent node [below] {}}
        child {node [outcome, label=right:{\$25}]{}
            edge from parent node [above] {}}
                    edge from parent node [above] {}};
\draw[dashed] (a)--(b);
\end{tikzpicture}
\end{document}

Answer 2

我推荐 forest，它的语法更简单，你不必担心这些事情。

\documentclass{article}
\usepackage[edges]{forest}
\tikzset{
    choice/.style = {shape=rectangle, draw, align=center, color=black, fill=black},
    chance/.style = {shape=circle, draw, align=center, color=black, fill=black},
    root/.style = {choice, font=\normalsize, color=black},
    outcome/.style = {shape=rectangle, draw=white, align=center, font=\tiny, parent anchor=left},
}

\begin{document}
\begin{forest}
for tree={grow'=east,edge={-latex},l+=1cm}
[,root
 [,choice
  [\$25]
  [,chance
   [,choice,edge label={node[midway,above,sloped]{.5}}
    [\$55]
    [\$45]
   ]
   [,choice,edge label={node[midway,below,sloped]{.5}}
    [\$100]
    [\$10]
   ]
  ]
 ]
 [\$30]
]
\end{forest}
\end{document}