Example: Series and parallel graph diagrams

%Author: Paul Thompson    06-08-2009
%   Series and Parallel graph diagrams using nesting of tikz-environments.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning,fit}
\begin{document}

\newcounter{parlevel}
\newcounter{serlevel}

%define a parallel block:  a tikz-pic with two nodes drawn on top of each other and some connecting lines
%the node contents comes from  #1 and #2
%the two nodes are named 'nTsp'  and 'nBsp'     where s and p are serial and parallel levels which increment
\newcommand{\parblock}[2]
{
   \tikz[baseline,remember picture,inner sep=0pt,outer sep=0pt,node distance=0.25cm]
   {
       \addtocounter{parlevel}{1}
       %special names for the two nodes:
       \def\nTsp{nT-\arabic{serlevel}-\arabic{parlevel}}
       \def\nBsp{nB-\arabic{serlevel}-\arabic{parlevel}}
       %
       %define the two nodes:
       \node(\nTsp){#1};
       \node[below=of \nTsp](\nBsp){#2};
       %
       %use bounding box so that the lines are based on the widest one
       \path (current bounding box.west) -- +(-0.125,0) coordinate (source);
       \path (current bounding box.east) -- +( 0.125,0) coordinate (dest);
       %
       %draw up/down and across from source (left)
       \draw (source) |- (\nTsp.west);
       \draw (source) |- (\nBsp.west);
       %
       %draw across and up/down to dest (right)
       \draw (\nTsp.east) -| (dest);
       \draw (\nBsp.east) -| (dest);
       %
       %add extra horizontal lines at source and dest
       \draw (source) -- +(-0.125,0);
       \draw (dest) -- +( 0.125,0);
       \addtocounter{parlevel}{-1}
   }
}


\newcommand{\block}[1]
{
   \tikz[baseline,remember picture,inner sep=2pt]
   {
       \node[draw,shape=rectangle](#1){#1};
   }
}

%define a series block:  a tikz-pic with two nodes drawn next to each other and some connecting lines
%the node contents comes from  #1 and #2
%the two nodes are named 'nAsp'  and 'nBsp'     where x,y are serial and parallel levels which increment
\newcommand{\serblock}[2]
{
   \tikz[baseline,remember picture,inner sep=0pt,outer sep=0pt,node distance=0.25cm]
   {
       \addtocounter{serlevel}{1}
       %special names for the two nodes:
       \def\nLsp{nL-\arabic{serlevel}-\arabic{parlevel}}
       \def\nRsp{nR-\arabic{serlevel}-\arabic{parlevel}}
       %
       %define the two nodes:
       \node(\nLsp){#1};
       \node[right=of \nLsp](\nRsp){#2};
       %
       %define source and dest just past the nAsp and nBsp nodes
       \path (\nLsp.west) -- +(-0.125,0) coordinate (source);
       \path (\nRsp.east) -- +( 0.125,0) coordinate (dest);
       %
       %add lines at extreme ends
       \draw (source) -- (\nLsp.west);
       \draw (\nLsp.east) -- (\nRsp.west);
       \draw (\nRsp.east) -- (dest);
       \addtocounter{serlevel}{-1}
   }
}



\begin{figure}
\centering
\parblock{\block{top}}{\block{bottom}}
\caption{Parallel block}
\end{figure}


\begin{figure}
\centering
\serblock{\block{left}}{\block{right}}
\caption{Series block}
\end{figure}


\begin{figure}
\centering
\parblock
{\serblock{\block{top-left}}{\block{top-right}}}
{\serblock{\block{bottom-left}}{\block{bottom-right}}}
\caption{Series blocks in parallel}
\end{figure}

\begin{figure}
\centering
\serblock
{\parblock{\block{left-top}}{\block{left-bottom}}}
{\parblock{\block{right-top}}{\block{right-bottom}}}
\caption{Parallel blocks in series}
\end{figure}

\begin{figure}
\centering
\serblock
{\serblock{\block{left-left}}{\block{left-right}}}
{\serblock{\block{right-left}}{\block{right-right}}}
\caption{Series blocks in series}
\end{figure}


\begin{figure}
\centering
\parblock
{\parblock{\block{top-top}}{\block{top-bottom}}}
{\parblock{\block{bottom-top}}{\block{bottom-bottom}}}
\caption{Parallel blocks in Parallel}
\end{figure}

\begin{figure}
\centering
\parblock
{\parblock{\parblock{\block{t-t-t}}{\block{t-t-b}}}{\parblock{\block{t-b-t}}{\block{t-b-b}}}}
{\parblock{\parblock{\block{b-t-t}}{\block{b-t-b}}}{\parblock{\block{b-b-t}}{\block{b-b-b}}}}
\caption{Parallel blocks in parallel, in parallel}
\end{figure}

\begin{figure}
\centering
\serblock
{\parblock{\parblock{\block{l-t-t}}{\block{l-t-b}}}{\parblock{\block{l-b-t}}{\block{l-b-b}}}}
{\parblock{\parblock{\block{r-t-t}}{\block{r-t-b}}}{\parblock{\block{r-b-t}}{\block{r-b-b}}}}
\caption{Parallel blocks in parallel, in series}
\end{figure}


\begin{figure}
\centering
\serblock
{\parblock{\serblock{\parblock{\serblock{\block{}}{\serblock{\parblock{\block{}}{\block{}}}{\block{}}}}
{\serblock{\parblock{\serblock{\parblock{\block{}}{\block{}}}{\block{}}}{\block{}}}{\block{}}}}
{\parblock{\serblock{\parblock{\block{}}{\block{}}}
{\block{}}}{\serblock{\parblock{\serblock{\block{}}{\block{}}}{\parblock{\block{}}{\block{}}}}
{\serblock{\block{}}{\block{}}}}}}
{\serblock{\parblock{\parblock{\serblock{\parblock{\serblock{\block{}}{\block{}}}{\serblock{\parblock{\block{}}{\block{}}}
{\block{}}}}{\parblock{\block{}}{\serblock{\parblock{\serblock{\block{}}{\block{}}}
{\parblock{\block{}}{\block{}}}}{\serblock{\block{}}{\block{}}}}}}
{\serblock{\parblock{\block{}}{\serblock{\parblock{\serblock{\block{}}{\block{}}}
{\parblock{\block{}}{\block{}}}}{\serblock{\block{}}{\block{}}}}}{\parblock{\serblock{\block{}}
{\block{}}}{\serblock{\parblock{\block{}}{\block{}}}{\block{}}}}}}{\serblock{\parblock{\serblock{\block{}}
{\block{}}}{\parblock{\block{}}{\block{}}}}{\serblock{\block{}}{\block{}}}}}
{\parblock{\serblock{\parblock{\serblock{\block{}}{\block{}}}{\serblock{\parblock{\block{}}
{\block{}}}{\block{}}}}{\serblock{\parblock{\block{}}{\block{}}}{\block{}}}}{\serblock{\parblock{\block{}}
{\block{}}}{\block{}}}}}}
{\parblock{\block{}}{\block{}}}

\caption[Series and Parallel graph diagram]{This example shows latex macros which nest tikz environments together to generate series and parallel graph diagrams.
This shows an example of latex-macros and nesting of tikz environments being used to draw large recursively-defined (nested) diagrams.}
\end{figure}

\end{document}