我需要有关 Forest 环境中应用程序的帮助。我想在 Forest 中创建一棵游戏树，其中有连续的移动。这些移动用弧线标记，如图上部所示（字母 B 上方）。我已经能够通过查看此处另一个问题的答案成功实现这一点。但是，在这个特定情况下，我想在字母 D 上方以相同的方式再画一条弧线。我认为我需要事先定义 Forest 不仅在级别 0 上这样做，而且在级别 2 上也这样做。但是，我已经尝试了不同的方法，但遗憾的是没有得到令人满意的结果。如果您继续使用现有代码（如果可能），并且不建议任何其他可能合适的环境，我将不胜感激。
\documentclass[tikz, border=10pt, multi]{standalone}
\usepackage{amsmath}
\usepackage{forest}
\usetikzlibrary{angles}
\usetikzlibrary{decorations.pathreplacing,calligraphy,backgrounds, through, calc}
\usetikzlibrary{through,calc}
%---------------------------------------------------------
\forestset{%
auto edge label/.style={%
before typesetting nodes={%
if level=0{}{
if={n()>(n_children("!u")/2)}{
if={n()==((n_children("!u")+1)/2)}{
edge label/.wrap value={
node[midway, right] {$##1$}
},
}{
edge label/.wrap value={
node[midway, outer sep=1.5mm, right] {$##1$}
},
},
}{
edge label/.wrap value={
node[midway, outer sep=1.5mm, left] {$##1$}
},
}
},
},
},
nice empty nodes/.style={% page 65 of the manual - this is from the linguistics library
for tree={
calign=fixed edge angles
},
delay={
where content={}{
shape=coordinate,
for parent={
for children={anchor=north}
}
}{}
}
},
arc below/.style={
tikz+={%
\clip (.center) coordinate (o) -- (!1.north) coordinate (a) |- (!2.north) coordinate (b) -| (!3.north) coordinate (c) -- cycle;
\node [draw, circle through={(b)}] at (o) {};
\draw [\forestoption{edge}] () -- ($(o)!1!-35:(b)$) ($(o)!1!35:(b)$) -- ();
},
for children={
if n=2{}{no edge},
}
}
}
\tikzset{%
my circle/.style={draw, circle}
}
\begin{document}
\begin{forest}
for tree={
l sep=2em,
s sep=4em,
auto edge label,
nice empty nodes,
math content
}
[A, my circle, arc below
[, coordinate, edge label={0}]
[B, my circle, edge label={}
[{C}, my circle, edge label=0,
[, coordinate , edge label={0}]
[D, my circle, edge label={}
[E, my circle, edge label={0}
[{0}, edge label={0}]
[{0}, edge label={0}]
]
[{0}, edge label={0}]
]
[ , coordinate, edge label={0}]
]
[{0}, edge label={0}]
]
[, coordinate, edge label={0}]
]
\end{forest}
\end{document}
答案1
为了在节点“C”下方绘制弧，我们只需arc below在其规范中添加即可。但是：
tikz+定义中的的内容arc below应包含在scope环境中，否则“A”弧的剪切将应用于图片的其余部分，包括“C”下方的预期弧。（请注意，“图片的其余部分”不包括节点“A”之后的节点（及其边），因为 Forest 首先绘制所有节点，然后绘制所有边，然后才绘制附加tikz代码。）
\documentclass[tikz, border=10pt, multi]{standalone}
\usepackage{amsmath}
\usepackage{forest}
\usetikzlibrary{angles}
\usetikzlibrary{decorations.pathreplacing,calligraphy,backgrounds, through, calc}
\usetikzlibrary{through,calc}
%---------------------------------------------------------
\forestset{%
auto edge label/.style={%
before typesetting nodes={%
if level=0{}{
if={n()>(n_children("!u")/2)}{
if={n()==((n_children("!u")+1)/2)}{
edge label/.wrap value={
node[midway, right] {$##1$}
},
}{
edge label/.wrap value={
node[midway, outer sep=1.5mm, right] {$##1$}
},
},
}{
edge label/.wrap value={
node[midway, outer sep=1.5mm, left] {$##1$}
},
}
},
},
},
nice empty nodes/.style={% page 65 of the manual - this is from the linguistics library
for tree={
calign=fixed edge angles
},
delay={
where content={}{
shape=coordinate,
for parent={
for children={anchor=north}
}
}{}
}
},
arc below/.style={
tikz+={%
\begin{scope}
\clip (.center) coordinate (o) -- (!1.north) coordinate (a) |- (!2.north) coordinate (b) -| (!3.north) coordinate (c) -- cycle;
\node [draw, circle through={(b)}] at (o) {};
\draw [\forestoption{edge}] () -- ($(o)!1!-35:(b)$) ($(o)!1!35:(b)$) -- ();
\end{scope}
},
for children={
if n=2{}{no edge},
}
}
}
\tikzset{%
my circle/.style={draw, circle}
}
\begin{document}
\begin{forest}
for tree={
l sep=2em,
s sep=4em,
auto edge label,
nice empty nodes,
math content
}
[A, my circle, arc below
[, coordinate, edge label={0}]
[B, my circle, edge label={}
[{C}, my circle, edge label=0, arc below,
[, coordinate , edge label={0}]
[D, my circle, edge label={}
[E, my circle, edge label={0}
[{0}, edge label={0}]
[{0}, edge label={0}]
]
[{0}, edge label={0}]
]
[ , coordinate, edge label={0}]
]
[{0}, edge label={0}]
]
[, coordinate, edge label={0}]
]
\end{forest}
\end{document}