# Centering Tikz tree

How do I center Tikz trees on the page, like the one used in the answer to this question:

Horizontal Probability Tree with Level Labels

Having modified that code to the below code, my tree is off-center and overflowing:

\tikzstyle{level 1}=[level distance=3.5cm, sibling distance=3.5cm]
\tikzstyle{level 2}=[level distance=4.5cm, sibling distance=1.5cm]
\tikzstyle{level 3}=[level distance=3.5cm, sibling distance=2cm]

\tikzstyle{bag} = [text width=4em, text centered]
\tikzstyle{end} = [rectangle, draw=none, minimum width=3pt, inner sep=0pt]

\tikzstyle{ans} = [color=red]

\begin{tikzpicture}[level distance=5cm,
level 1/.style={sibling distance=3.5cm},
level 2/.style={sibling distance=1.2cm},
level 3/.style={level distance = 2cm},grow'=right]
\tikzstyle{every node}=[]
\node (Root) [] {Origin}
child [] {
node {Door A}
child { node {A}
child {node[end] {AAB ({\color{red} 1/18})}
edge from parent
node[ans,left] {$1/2$}}
child {node[end] {AAC ({\color{red} 1/18})}
edge from parent
node[ans,left] {$1/2$}}
edge from parent
node[ans,left] {$1/3$}
}
child [black] { node {B}
child {node[end] {ABC ({\color{red} 1/9})}
edge from parent
node[ans,left] {$1$}}
edge from parent
node[ans,left] {$1/3$}
}
child [black] { node {C}
child {node[end] {ACB ({\color{red} 1/9})}
edge from parent
node[ans,left] {$1$}}
edge from parent
node[ans,left] {$1/3$}
}
edge from parent
node[ans,above] {$1/3$}
}
child {
node {Door B}
child { node {A}
child {node[end] {BAC ({\color{red} 1/9})}
edge from parent
node[ans,left] {$1$}
}
edge from parent
node[ans,left] {$1/3$}
}
child { node {B}
child {node[end] {BBA ({\color{red} 1/18})}
edge from parent
node[ans,left] {$1/2$}}
child {node[end] {BBC ({\color{red} 1/18})}
edge from parent
node[ans,left] {$1/2$}}
edge from parent
node[ans,left] {$1/3$}
}
child { node {C}
child {node[end] {BCA ({\color{red} 1/9})}
edge from parent
node[ans,left] {$1$}}
edge from parent
node[ans,left] {$1/3$}
}
edge from parent
node[ans,above] {$1/3$}
}
child {
node {Door C}
child { node {A}
child {node[end] {CAB ({\color{red} 1/9})}
edge from parent
node[ans,left] {$1$}}
edge from parent
node[ans,left] {$1/3$}
}
child { node {B}
child {node[end] {CBA ({\color{red} 1/9})}
edge from parent
node[ans,left] {$1$}}
edge from parent
node[ans,left] {$1/3$}
}
child { node {C}
child {node[end] {CCA ({\color{red} 1/18})}
edge from parent
node[ans,left] {$1/2$}}
child {node[end] {CCB ({\color{red} 1/18})}
edge from parent
node[ans,left] {$1/2$}}
edge from parent
node[ans,left] {$1/3$}
}
edge from parent
node[ans,above] {$1/3$}
};
% How I'm applying labels to each level.
% Need to be able to dynamically align nodes at top level
\begin{scope}[every node/.style={text width=2cm, align=center, anchor=center, font=\bfseries,}]
\node[above= 1cm of Root-1-1-1] (labels-level) {Monty's pick / Outcome};
\node[at =(labels-level-|Root-1-1)] {Contestant picked};
\node[at =(labels-level-|Root-1)] {Prize is behind};
\node[at =(labels-level-|Root)] {};

\end{scope}
\end{tikzpicture}


• Welcome to TeX-SE! In order to see to which extent the tree overshoots the boundaries of your document we need to see the specifics. Therefore please add a fully compilable code that starts with \documentclass and ends with \end{document}. Otherwise we won't know what the page parameters are, nor the font size. (Side remark: \tikzstyle is deprecated.)
– user121799
Jun 21 '19 at 2:04

I do not know if this goes in the right direction but at least it is a complete compilable example that does not go out of bounds.

\documentclass{article}
\usepackage[showframe]{geometry}
\usepackage{tikz}
\usetikzlibrary{positioning,trees}
\tikzset{level 1/.style={level distance=3.5cm, sibling distance=3.5cm},
level 2/.style={level distance=4.5cm, sibling distance=1.5cm},
level 3/.style={level distance=3.5cm, sibling distance=2cm},
bag/.style = {text width=4em, text centered},
end/.style = {rectangle, draw=none, minimum width=3pt, inner sep=0pt,right},
ans/.style = {color=red}}
\begin{document}
\begin{tikzpicture}[level distance=2.5cm,
level 1/.style={sibling distance=3.5cm},
level 2/.style={sibling distance=1.2cm},
level 3/.style={level distance = 2cm},grow'=right]
\tikzstyle{every node}=[]
\node (Root) [] {Origin}
child [] {
node {Door A}
child { node {A}
child {node[end] {AAB (\textcolor{red}{1/18})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/2$}}
child {node[end] {AAC (\textcolor{red}{1/18})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/2$}}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
child [black] { node {B}
child {node[end] {ABC (\textcolor{red}{1/9})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1$}}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
child [black] { node {C}
child {node[end] {ACB (\textcolor{red}{1/9})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1$}}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
child {
node {Door B}
child { node {A}
child {node[end] {BAC (\textcolor{red}{1/9})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1$}
}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
child { node {B}
child {node[end] {BBA (\textcolor{red}{1/18})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/2$}}
child {node[end] {BBC (\textcolor{red}{1/18})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/2$}}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
child { node {C}
child {node[end] {BCA (\textcolor{red}{1/9})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1$}}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
child {
node {Door C}
child { node {A}
child {node[end] {CAB (\textcolor{red}{1/9})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1$}}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
child { node {B}
child {node[end] {CBA (\textcolor{red}{1/9})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1$}}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
child { node {C}
child {node[end] {CCA (\textcolor{red}{1/18})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/2$}}
child {node[end] {CCB (\textcolor{red}{1/18})}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/2$}}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
}
edge from parent
node[ans,pos=0.7,above,sloped] {$1/3$}
};
% How I'm applying labels to each level.
% Need to be able to dynamically align nodes at top level
\begin{scope}[every node/.style={text width=2cm, align=center, anchor=center, font=\bfseries,}]
\node[above= 1cm of Root-1-1-1] (labels-level) {Monty's pick / Outcome};
\node[at =(labels-level-|Root-1-1)] {Contestant picked};
\node[at =(labels-level-|Root-1)] {Prize is behind};
\node[at =(labels-level-|Root)] {};

\end{scope}
\end{tikzpicture}
\end{document}


My personal favorite for drawing such trees, though, is forest.

\documentclass{article}
\usepackage[showframe]{geometry}
\usepackage{forest}
\usetikzlibrary{positioning}
\forestset{el/.style={edge label={node[above,pos=0.7,sloped,font=\sffamily\small,text=red]{#1}}},
el'/.style={edge label={node[below,pos=0.7,sloped,font=\sffamily\small,text=red]{#1}}}}
\tikzset{mono/.style={/tikz/execute at end node={~(\textcolor{red}{1/9})}},
duo/.style={/tikz/execute at end node={~(\textcolor{red}{1/18})}}}
\begin{document}
\begin{forest}
for tree={grow'=0,where level=1{l+=3em}{l+=2em},
if level=3{}{el={1/3}},}
[Origin,alias=l0
[Door A,alias=l1
[A,alias=l2
[AAB,el=1/2,duo,alias=l3]
[AAC,el'=1/2,duo]
]
[B
[ABC,el=1,mono]
]
[C
[ACB,el=1,mono]
]
]
[Door B
[A
[BAC,el=1,mono]
]
[B
[BBA,el=1/2,duo]
[BBC,el'=1/2,duo]
]
[C
[BCA,el=1,mono]
]
]
[Door C
[A
[CBA,el=1,mono]
]
[B
[CAB,el=1,mono]
]
[C
[CCA,el=1/2,duo]
[CCB,el'=1/2,duo]
]
]
]
\begin{scope}[every node/.style={text width=2cm,align=center, anchor=center, font=\bfseries}]
\node[above= 1cm of l3] (labels-level) {Monty's pick / Outcome};
\node[at =(labels-level-|l2)] {Contestant picked};
\node[at =(labels-level-|l1)] {Prize is behind};
\node[at =(labels-level-|l0)] {};
\end{scope}
\end{forest}
\end{document}


The frame can be removed by removing showframe (or \usepackage[showframe]{geometry} altogether). This example does, by far, not show all the powers of forest.

• Good to see 2 alternatives! As a side note, I think the red labels are a bit shifted. Why not use midway for these cases? Jun 21 '19 at 5:48
• @manooooh If you look at the connection Door C to B you see why. (One could solve this by putting the labels manually.)
– user121799
Jun 21 '19 at 5:50