Tikz Forest 着色和边缘标签位置

Question

以下是代码：

\begin{figure}[H]\centering
    \begin{tikzpicture}
        \node (tree)
        {
            \begin{forest}
                for tree = {circle, draw, minimum width = 2.25em}
                    [\textcolor{red}{$S$}
                        [$A$, edge label = {node [midway, above left, font = \scriptsize] {\textcolor{red}{$1$}}}
                            [$B$, edge label = {node [midway, above left, font = \scriptsize] {$4$}}
                                [$D_1$, edge label = {node [midway, left, font = \scriptsize] {$7$}}
                                    [$G_1$, edge label = {node [midway, left, font = \scriptsize] {$10$}}]
                                ]
                            ]
                            [$C$, edge label = {node [midway, above right, font = \scriptsize] {$2$}}
                                [$D_2$, edge label = {node [midway, above left, font = \scriptsize] {$3$}}
                                    [$G_2$, edge label = {node [midway, left, font = \scriptsize] {$6$}}]
                                ]
                                [$G_3$, edge label = {node [midway, above right, font = \scriptsize] {$4$}}]
                            ]
                        ]
                        [$G_4$, edge label = {node [midway, above right, font = \scriptsize] {$12$}}]
                   ]
        \end{forest}
    };
\end{tikzpicture}

输出如下：

以下是与此相关的几个问题：

1. 我想将节点（圆圈）的边界涂成红色，并将一些边缘涂成红色。有办法吗？

2. 对于边缘标签，对于水平和垂直位置，如node[midway, right]或中node[midway, above]，这分别适用于垂直和水平边缘，但对于倾斜的边缘，因为它们可以承担任何角度，我想标记边缘，使它们成为与水平和垂直标签的距离相同， 但在垂直方向到倾斜的边缘。如何对其进行编码？

3. 如何让边长更长？对于所有边？对于某些边？

任何帮助都将不胜感激。提前谢谢您！

Answer 1

好吧，这是一片森林，有红色圆圈节点（draw=red）、一个更大的l sep（l sep+=2em）和圆形边缘标签，以确保通用距离。我还将一条边涂成蓝色。您可以添加s sep+=1em等等。

\documentclass{article}
\usepackage[edges]{forest}
\begin{document}
\tikzset{eln/.style={midway, font = \scriptsize,circle,inner sep=2pt}}
\begin{forest}
for tree = {circle, 
    draw=red, %<-added =red
    minimum width = 2.25em,
    l sep+=2em
}
    [\textcolor{red}{$S$}
        [$A$, edge label = {node [above left,eln] {\textcolor{red}{$1$}}}
            [$B$, edge label = {node [above left,eln] {$4$}}
                [$D_1$, edge label = {node [left,eln] {$7$}}
                    [$G_1$, edge label = {node [left,eln] {$10$}}]
                ]
            ]
            [$C$, edge label = {node [above right,eln] {$2$}},edge=blue%<-blue edge
                [$D_2$, edge label = {node [above left,eln] {$3$}}
                    [$G_2$, edge label = {node [left,eln] {$6$}}]
                ]
                [$G_3$, edge label = {node [above right,eln] {$4$}}]
            ]
        ]
        [$G_4$, edge label = {node [above right,eln] {$12$}}]
   ]
\end{forest}
\end{document}

或者只为特定节点着色。

\documentclass{article}
\usepackage[edges]{forest}
\begin{document}
\tikzset{eln/.style={midway, font = \scriptsize,circle,inner sep=2pt}}
\begin{forest}
for tree = {circle, 
    draw,%
    minimum width = 2.25em,
    l sep+=2em
}
    [\textcolor{red}{$S$}
        [$A$, edge label = {node [above left,eln] {\textcolor{red}{$1$}}}
            [$B$, edge label = {node [above left,eln] {$4$}}
                [$D_1$, edge label = {node [left,eln] {$7$}}
                    [$G_1$, edge label = {node [left,eln] {$10$}}]
                ]
            ]
            [$C$,draw=red, edge label = {node [above right,eln] {$2$}},edge=blue%<-blue edge
                [$D_2$, edge label = {node [above left,eln] {$3$}}
                    [$G_2$, edge label = {node [left,eln] {$6$}}]
                ]
                [$G_3$, edge label = {node [above right,eln] {$4$}}]
            ]
        ]
        [$G_4$, edge label = {node [above right,eln] {$12$}}]
   ]
\end{forest}
\end{document}