Tikz-qtree：在屋顶下用不同的单词绘制箭头

Question

我想从屋顶下的不同单词画出箭头。在我的例子中，“Mary saw who”在屋顶下，我希望从“Mary”画出一个箭头，从“who”画出另一个箭头，指向树中更上层的“Mary”和“who”。我无法将单独的单词标记为屋顶下的节点，只能将整个短语标记为节点（如我的例子所示）。当我这样做时，我可以通过更改值或坐标来绘制一个箭头，以便操纵它从“who”和“saw”指向[xshift]，但出于某种原因，我无法让它从“Mary”指向。

\documentclass{report}  
\usepackage{tikz-qtree}  
\usepackage{tikz-qtree-compat}  

\begin{document}

\begin{tikzpicture}  
\tikzset{every tree node/.style={align=center,anchor=north}}  
\Tree   
[.CP [.specCP \node(wh){$[$Q, $\phi$^{\textsc{epp}} $]$ \\ who}; ]    
[.C\1 [.C  ]  
[.TP [.DP \node(DP2){Mary}; ]  
[.T\1 [.T saw ]  
[.$v$P [.DP \node(wh2){who}; ]  
[.$v$\1 \edge[roof];  \node(x){Mary saw who}; ]  
  ] ] ] ] ] ]   
 \draw [->] ([xshift=0.1em]x.south) to[out=-90,in=-90,looseness=2] (DP2.south);  
 \draw [->] (x.south)++(1,0) to[out=-90,in=-90,looseness=2] (wh2.south);  

\end{tikzpicture}

\end{document}

Answer 1

您可以x.south使用x.south west和x.south east来更轻松地定位箭头的起点。经过一些测试，我得到了：

\documentclass{report}  
\usepackage{tikz-qtree}  
\usepackage{tikz-qtree-compat}  

\begin{document}

\begin{tikzpicture}  
\tikzset{every tree node/.style={align=center,anchor=north}}  
\Tree   
[.CP [.specCP \node(wh){$[$Q, $\phi$^{\textsc{epp}} $]$ \\ who}; ]    
[.C\1 [.C  ]  
[.TP [.DP \node(DP2){Mary}; ]  
[.T\1 [.T saw ]  
[.$v$P [.DP \node(wh2){who}; ]  
[.$v$\1 \edge[roof];  \node(x){Mary saw who}; ]  
  ] ] ] ] ] ]   
 \draw [->] ([xshift=1.75em]x.south west) to[out=-90,in=-90,looseness=2] (DP2.south);  
 \draw [->]  ([xshift=-1em]x.south east) to[out=-90,in=-90,looseness=2] (wh2.south);  

\end{tikzpicture}

\end{document}