子图中的 Tikz 树间距

子图中的 Tikz 树间距

我一直在尝试以如下所示的子图格式创建决策树,但无论我尝试哪种间距,总会在某个点或另一个点出现重叠节点。在下面的示例中,我有同一棵树的两个副本作为示例。如何使用 tikz 包修复此问题?此外,对于使用 tikz 包绘制稍大的树,有什么建议吗?这非常令人沮丧,因为我觉得我正处于随机更改级别/兄弟距离以尝试让事情正常运转的阶段……

\documentclass{book}
\usepackage{tikz}
\usepackage{amsmath,amssymb,amstext,amsthm}
\usepackage{subcaption}
\begin{document}
\begin{figure}
\centering
\begin{subfigure}[h]{0.475\textwidth}
\centering
\begin{tikzpicture}[scale=0.6, level distance=25mm,
    level 1/.style={sibling distance=80mm},
    level 2/.style={sibling distance=50mm},
    level 3/.style={sibling distance=30mm}]
\node[circle, draw]{$x\smash{_1}$}
    child{node[circle, draw]{$x\smash{_2}$}
        child{node[circle, draw]{$x\smash{_4}$}
            child{node[rectangle, draw]{$x\smash{_1} \gets 1$}}
            child{node[rectangle, draw]{$x\smash{_2} \gets 1$}} 
        }
        child{node[circle, draw]{$x\smash{_4}$}
            child{node[rectangle, draw]{$x\smash{_1} \gets 1$}}
            child{node[rectangle, draw]{$x\smash{_4} \gets 0$}} 
        }   
    }
    child{node[circle, draw]{$x\smash{_3}$}
        child{node[circle, draw]{$x\smash{_2}$}
            child{node[rectangle, draw]{$\begin{aligned} x\smash{_1} &\gets 0 \\ x\smash{_3} &\gets 1 \end{aligned}$}}
            child{node[rectangle, draw]{$\begin{aligned} x\smash{_1} &\gets 0 \\ x\smash{_2} &\gets 0 \end{aligned}$}}  
        }
        child{node[circle, draw]{$x\smash{_4}$}
            child{node[rectangle, draw]{$x\smash{_4} \gets 1$}}
            child{node[rectangle, draw]{$x\smash{_3} \gets 0$}} 
        }   
    }
;
\end{tikzpicture}
\caption{A Tree}
\end{subfigure}
\begin{subfigure}[h]{0.475\textwidth}
\centering
\begin{tikzpicture}[scale=0.6, level distance=25mm,
    level 1/.style={sibling distance=80mm},
    level 2/.style={sibling distance=50mm},
    level 3/.style={sibling distance=30mm}]
\node[circle, draw]{$x\smash{_1}$}
    child{node[circle, draw]{$x\smash{_2}$}
        child{node[circle, draw]{$x\smash{_4}$}
            child{node[rectangle, draw]{$x\smash{_1} \gets 1$}}
            child{node[rectangle, draw]{$x\smash{_2} \gets 1$}} 
        }
        child{node[circle, draw]{$x\smash{_4}$}
            child{node[rectangle, draw]{$x\smash{_1} \gets 1$}}
            child{node[rectangle, draw]{$x\smash{_4} \gets 0$}} 
        }   
    }
    child{node[circle, draw]{$x\smash{_3}$}
        child{node[circle, draw]{$x\smash{_2}$}
            child{node[rectangle, draw]{$\begin{aligned} x\smash{_1} &\gets 0 \\ x\smash{_3} &\gets 1 \end{aligned}$}}
            child{node[rectangle, draw]{$\begin{aligned} x\smash{_1} &\gets 0 \\ x\smash{_2} &\gets 0 \end{aligned}$}}  
        }
        child{node[circle, draw]{$x\smash{_4}$}
            child{node[rectangle, draw]{$x\smash{_4} \gets 1$}}
            child{node[rectangle, draw]{$x\smash{_3} \gets 0$}} 
        }   
    }
;
\end{tikzpicture}
\caption{B Tree}
\end{subfigure}
\caption{Caption}
\label{datftt}
\end{figure}
\end{document}

答案1

最终,树的最小宽度取决于叶节点(末端)内的文本。对于这两棵树,您可以看到,将所有端到端的x_n <- 1结果放置在一起已经占用了文本宽度的一半以上。如果您想强制这些树并排放置,则要么有重叠的树(如您目前所做的那样),要么有重叠的节点。这两种选择都不优雅……

可以通过为较低级别设置较小的字体大小来稍微调整此最小宽度,以便它们并排放置时占用更少的空间。这可以通过 来实现level n/.style={font=\footnotesize}

您还提到,您必须不断尝试调整兄弟距离。原因是 Ti 中的标准树构造算法Z 的预见能力很差。它看到下一级有n节点,并根据兄弟距离放置它们,但它不知道这些节点下面是否还有更多节点,从而使得节点的有效“宽度”更大。

可以使用graph drawing这个问题可以通过使用Ti 中的库Z.它提供了更多的算法来自动放置节点,这使得绘图图表 简单得多。我提供了一个示例来展示如何使用图形绘制库:

\documentclass{book}
\usepackage{tikz}
\usetikzlibrary{
  graphs,
  graphdrawing,
}
\usegdlibrary{trees}
\usepackage{amsmath,amssymb,amstext,amsthm}
\usepackage{subcaption}
\begin{document}
\begin{figure}
  \centering
  \begin{subfigure}[b]{\linewidth}
    \centering
    \tikz \graph [
      tree layout,
      nodes={
        draw,
        circle,
      },
      level 3/.style={
        font=\small,
      },
      level 4/.style={
        nodes={
          rectangle,
          font=\footnotesize,
        }
      }
    ] {
      "\(x_{}\)"
        -> {
          "\(x_{1}\)"
          -> {
            "\(x_{11}\)"
            -> {
              "\(x_{111}\)",
              "\(x_{112}\)"
            },
            "\(x_{12}\)"
            -> {
              "\(x_{121}\)",
              "\(x_{122}\)"
            }
          },
          "\(x_{2}\)"
          -> {
            "\(x_{21}\)"
            -> {
              "\(x_{211}\)",
              "\(x_{212}\)"
            },
            "\(x_{22}\)"
            -> {
              "\(x_{221}\)",
              "\(x_{222}\)"
            }
          }
        }
    };
    \caption{Tree \(x\)}
  \end{subfigure}

  \begin{subfigure}[b]{\linewidth}
    \centering
    \tikz \graph [
      tree layout,
      nodes={
        draw,
        circle,
      },
      level 3/.style={
        font=\small,
      },
      level 4/.style={
        nodes={
          rectangle,
          font=\footnotesize,
        }
      }
    ] {
      "\(y_{}\)"
        -> {
          "\(y_{1}\)"
          -> {
            "\(y_{11}\)"
            -> {
              "\(y_{111}\)",
              "\(y_{112}\)"
            },
            "\(y_{12}\)"
            -> {
              "\(y_{121}\)",
              "\(y_{122}\)"
            }
          },
          "\(y_{2}\)"
          -> {
            "\(y_{21}\)"
            -> {
              "\(y_{211}\)",
              "\(y_{212}\)"
            },
            "\(y_{22}\)"
            -> {
              "\(y_{221}\)",
              "\(y_{222}\)"
            }
          }
        }
    };
    \caption{Tree \(y\)}
  \end{subfigure}
  \caption{My awesome captions for trees!}
  \label{fig:trees}
\end{figure}
\end{document}

输出:

输出

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