# How to nest a graph within a node in TikZ and draw edges between the graphs?

I'm trying to draw a graph and have a separate graph within one of the outer nodes. I seen this question, but I don't understand how the matrix nodes will help me. I would also like to draw edges between the outer nodes to the inner nodes.

Could someone please make a quick example of with 3 nodes, where one of the nodes contains a subgraph with 3 nodes?

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Here's a little example: two "outer" nodes, each one containing a graph (formed with "inner" nodes) and some edges and arrows connecting outer nodes to outer nodes, and inner nodes from one graph to inner nodes of the other; the remember picture option lets you access inner and outer nodes at any time:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning,calc}

\begin{document}

\begin{tikzpicture}[remember picture,
inner/.style={circle,draw=blue!50,fill=blue!20,thick,inner sep=3pt},
outer/.style={draw=green,fill=green!20,thick,inner sep=10pt}
]
\node[outer,draw=green] (A) {
\begin{tikzpicture}
\node [inner,draw=blue] (ai)  {A1};
\node [inner,draw=blue,below=of ai] (aii) {A2};
\node [inner,draw=blue,right=of aii] (aiii) {A3};
\draw[red,thick] (ai) -- (aii) -- (aiii) -- (ai);
\end{tikzpicture}
};
\node[outer,draw=green,right=of A] (B) {
\begin{tikzpicture}
\node [inner,draw=blue] (bi)  {B1};
\node [inner,draw=blue,below=of bi] (bii) {B2};
\node [inner,draw=blue,right=of bii] (biii) {B3};
\node [inner,draw=blue,right=of bi] (biv) {B4};
\draw[red,thick] (bi) -- (bii) -- (biii) -- (biv) -- (bi) -- (biii);
\end{tikzpicture}
};
\draw[thick,orange,->] (ai) -- (bii);
\draw[orange,->] (aiii) -- (bi);
\draw[orange,->] (A.90) -- ($(A.90)+(0,1)$) -| (B);
\end{tikzpicture}

\end{document}


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Yep, this did it; remember picture was the key! Thanks! – gablin Sep 7 '11 at 19:11
This does work with pdflatex but not with latex--dvipdf. See here: tex.stackexchange.com/q/186583/34812 – user34812 Jun 25 '14 at 15:24

I don't know the kind of problems that OP has with TiKZ matrices but Gonzalo's example is the kind of graph where a matrix is really helpful.

\documentclass[border=3mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning,matrix}

\begin{document}

\begin{tikzpicture}[
inner/.style={circle,draw=blue!50,fill=blue!20,thick,inner sep=3pt},
outer/.style={draw=green,fill=green!20,thick,inner sep=10pt, column sep=1cm, row sep=1cm}
]
\matrix (A) [matrix of nodes, outer, nodes={inner}]{
A1 \\
A2 & A3\\
};

\matrix (B) [matrix of nodes, outer, nodes={inner}, right=of A]{
B1 & B4\\
B2 & B3\\
};

\draw[red, thick] (A-1-1)--(A-2-1)--(A-2-2)--(A-1-1);
\draw[red, thick] (B-1-1)--(B-1-2)--(B-2-2)--(B-2-1)--(B-1-1);
\draw[thick, orange,->] (A-1-1)--(B-2-1);
\draw[thick, orange,->] (A-2-2)--(B-1-1);
\draw[thick, orange,->] (A.north)--([yshift=1cm]A.north)-|(B);
\end{tikzpicture}

\end{document}


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