Tikz- Transitions around whole automaton

Question

I have following automaton in Tikz:

Is it possible to do a transition similar to this one?

Here's my code:

\begin{tikzpicture}[>=stealth,node distance=2.7cm,auto]
    \node[state,initial,accepting]  (I)                      {$I$};
    \node[state]                    (p) [above right of = I] {$p$};
    \node[state]                    (q) [right of = p]       {$q$};
    \node[state]                    (r) [below right of = I] {$r$};
    \node[state,accepting]          (F) [below right of = q] {$F$};

    \path[->]
        (I) edge                    node {a}     (p)
            edge                    node {b}     (r)
        (p) edge                    node {b}     (q)
            edge [swap, bend right] node {abc}   (F)
        (q) edge [bend left]        node {aabc}  (F)
            edge [swap, bend right] node {c}     (F)
        (r) edge                    node {aabc}  (F)
            edge [swap, bend right] node {c}     (F);   
\end{tikzpicture}

\draw[->] (I) -- ++(0,-3) -| (F) node[below,pos=0.25] {c}; (you might need to adjust the -3 part to clear all the edges). — Paul Gessler, Apr 08 '16 at 20:39
Certainly. See for example How to draw a return arrow from node-3 to node-1 -- Tikz: two edges path connection -- Is there a TikZ equivalent to the PSTricks \ncbar command? -- Vertical and horizontal lines in pgf-tikz and there are probably others around as well. — Torbjørn T., Apr 08 '16 at 20:39
Possible duplicate of How to draw a return arrow from node-3 to node-1 — Stefan Pinnow, Apr 08 '16 at 20:43
Related: https://tex.stackexchange.com/questions/45347/vertical-and-horizontal-lines-in-pgf-tikz — Henri Menke, Apr 09 '16 at 11:04
@PaulGessler I would accept one of the answers, but your comment is the only solution that worked for me. — Saraph, Apr 12 '16 at 21:10

Zarko · Answer 1 · 2016-04-08T23:06:55.947

Like this:

This is simple. Nodes in automaton are as other nodes in tikzpictures, so you can draw lines between them as you wish. In this case with help |- , yshift and -| between nodes I, r and F:

\documentclass[border=3mm,tikz]{standalone}
\usetikzlibrary{automata}

\begin{document}
\begin{tikzpicture}[>=stealth,node distance=2.7cm,auto]
    \node[state,initial,accepting]  (I)                      {$I$};
    \node[state]                    (p) [above right of = I] {$p$};
    \node[state]                    (q) [right of = p]       {$q$};
    \node[state]                    (r) [below right of = I] {$r$};
    \node[state,accepting]          (F) [below right of = q] {$F$};

    \path[->]
        (I) edge                    node {a} (p)
            edge                    node {b}     (r)
        (p) edge                    node {b}     (q)
            edge [swap, bend right] node {abc}   (F)
        (q) edge [bend left]        node {aabc}  (F)
            edge [swap, bend right] node {c}     (F)
        (r) edge                    node {aabc}  (F)
            edge [swap, bend right] node {c}     (F);
\draw[red,thick,->] (I) |- ([yshift=-5mm] r.south) -| (F);% <-- added
\end{tikzpicture}
    \end{document}

score 0 · Answer 2 · answered Apr 09 '16 at 12:24

Zarko's solution is fine is good but I prefried a solution that automatically calculates the correct placement this solution use fit library

\documentclass[border=3mm,tikz]{standalone}
\usetikzlibrary{automata}

\usetikzlibrary{fit}

\begin{document}
\begin{tikzpicture}[>=stealth,node distance=2.7cm,auto]
    \node[state,initial,accepting]  (I)                      {$I$};
    \node[state]                    (p) [above right of = I] {$p$};
    \node[state]                    (q) [right of = p]       {$q$};
    \node[state]                    (r) [below right of = I] {$r$};
    \node[state,accepting]          (F) [below right of = q] {$F$};

    \path[->]
        (I) edge                    node {a} (p)
            edge                    node {b}     (r)
        (p) edge                    node {b}     (q)
            edge [swap, bend right] node {abc}   (F)
        (q) edge [bend left]        node {aabc}  (F)
            edge [swap, bend right] node {c}     (F)
        (r) edge                    node {aabc}  (F)
            edge [swap, bend right] node {c}     (F);


\node[fit=(p) (r) (q) (F) (I)](all){};
\draw[red] (F) |-(all.south) -| (I);
\end{tikzpicture}
    \end{document}

Tikz- Transitions around whole automaton

2 Answers2