How to add text above the lines nodes in LaTeX

Question

I have following code and I try to add text above the edges, but don't how to do it

\begin{tikzpicture}[every tree node/.style={draw,circle},sibling
distance=30pt, level distance=50pt]
\tikzset{edge from parent/.style={draw, edge from parent path=
    {(\tikzparentnode) -- (\tikzchildnode)}}}
\Tree [.$n_{0}$  [.$n_{1}$ ] [.$n_{2}$ ] ]
\end{tikzpicture}

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score 1 · Accepted Answer · answered Mar 19 '22 at 06:30

Probably you use tikz-qtree package ... unfortunately its documentation doesn't describe, how to add edge labels. But by searching on this site you can find answer on question positioning-labels-on-edges-of-tikz-qtree which can be simple adopt to your case:

\documentclass[border=3.141502]{standalone}
\usepackage{tikz}
\usepackage{tikz-qtree}
\begin{document}
\begin{tikzpicture}[every tree node/.style={draw,circle},
   level distance=1.25cm,sibling distance=1cm,
   edge from parent path={(\tikzparentnode) -- (\tikzchildnode)}
                    ]
\Tree [.$n_{0}$ 
        \edge node[left] {$A$}; 
        [.$n_{1}$ ]
           \edge node[right] {$B$};
        [.$n_{2}$ ]
    ]
\end{tikzpicture}
\end{document}

However, there is also alternative solution with use of the forest package. Using it adding labels to edges is relatively simple:

\documentclass[border=3.141502]{standalone}
\usepackage{forest}
\begin{document}
    \begin{forest}
for tree = {
% nodes style
    circle, draw, inner sep=2pt,
    minimum size=1.2em,
    math content,
% tree style
    l sep = 9mm,
    s sep = 12mm,
/tikz/ELS/.style = {% Edge Label Style
    node font=\scriptsize, inner sep=1pt,
    pos=0.6, anchor=south #1},
EL/.style={if n=1{edge label={node[ELS=east]{$#1$}}}
                 {edge label={node[ELS=west]{$#1$}}}}
           }
[n_{0}
    [n_{1}, EL=A] 
    [n_{2}, EL=B] 
]
    \end{forest}
\end{document}

How to add text above the lines nodes in LaTeX

1 Answers1