How to draw state transition diagrams like this?
I had a go at not only duplicating the style but also simplifying the code for increased ease of consistency/reusability.
I defined three styles: transition, state, and statecolor. transition is to be used for connecting arrows, and state for plain states such as E in this diagram. statecolor inherits all settings from the state style, but adds fill and draw colors based on an argument passed into the style key like so: statecolor=red.
>=stealth sets stealth arrow tips globally. node distance=2, on grid sets the positioning library up for nodes 2cm apart, center-to-center.
I converted each positioned node to use the preferred =of syntax for use with the positioning library. I also added the calc library to negate the need for the temporary coordinates on the node edges. If many states have multiple transitions, it may be convenient to add additional anchors to the shape, as described in Add more anchors to standard Tikz nodes.
The complete revised code:
\documentclass[tikz]{standalone}
\usetikzlibrary{calc,positioning}
\tikzset{
transition/.style={font=\footnotesize, auto, inner sep=0.5ex},
state/.style={font=\large, minimum size=1cm, draw, fill=white},
statecolor/.style={state, draw=#1!70, fill=#1!30},
}
\begin{document}
\begin{tikzpicture}[>=stealth, node distance=2, on grid]
\node (S) [statecolor=blue] {$S$};
\node (E) [right=of S,state] {$E$};
\node (Z) [right=of E,statecolor=red] {$Z$};
\node (V) [right=of Z,statecolor=green] {$V$};
\draw[<-] (S) to +(-1,0) node[transition,left] {$\pi (S+V)$};
\draw[->] ($(S.east)!0.5!(S.north east)$) to node[transition] {$\beta SZ$} ($(E.west)!0.5!(E.north west)$);
\draw[->] ($(S.east)!0.5!(S.south east)$) to[swap,transition] node {$\delta S$} ($(E.west)!0.5!(E.south west)$);
\draw[->] (Z) to +(0,-1) node[transition,below] {$\gamma (S+ V)Z$};
\draw[->] (E) to +(0,-1) node[transition,below] {$(1-\alpha)\chi E$};
\draw[->] (E) to node[transition] { $\alpha\lambda E$} (Z);
\draw[->] (S) -- +(0,1) -| node[pos=0.25,transition] {$\zeta S$} (V);
\draw[->] ($(V.south)!0.5!(V.south east)$) to +(0,-1) node[transition,below] {$\beta VZ$};
\draw[->] ($(V.south)!0.5!(V.south west)$) to +(0,-0.5) node[transition,below] {$\delta V$};
\end{tikzpicture}
\end{document}
Update: Add a style file for my rect that can change the size of the rectangle. Also, it seems that node (7) is not needed and marked out in this new update.
\tikzset{my rect/.style={draw,shape=rectangle, minimum width=1cm, minimum height=1cm}}
Code
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{babel,positioning,shapes,calc}
\tikzset{my rect/.style={draw,shape=rectangle, minimum width=1cm, minimum height=1cm}}
\begin{document}
\begin{tikzpicture}
\tikzset{node distance=2.3cm, auto}
\node (0) {\footnotesize$\pi (S+V)$};
\node (1) [right of=0, xshift = -0.5cm, my rect,draw=black, fill=cyan!30!white] {$S$};
\node (2) [right of=1, my rect, draw=gray, fill=white] {$E$};
\node (3) [right of=2, my rect, draw=red, fill = red!30!white] {$Z$};
\node (4) [below of=2, yshift=1cm] {\footnotesize$(1-\alpha)\chi E$};
\node (5) [below of=3, yshift=1cm] {\footnotesize$\gamma (S+ V)Z$};
\node (6) [right of = 3, draw=green, my rect, fill = green!30!white] {$V$};
%\node (7) [below of=6, yshift=1cm, text = white] {$V$};
\path (1.east) -- (1.north east) coordinate[pos=0.5] (a1);
\path (2.west) -- (2.north west) coordinate[pos=0.5] (b1);
%\path (6.south) -- (6.south east) coordinate[pos=0.5] (a6);
%\path (6.south) -- (6.south west) coordinate[pos=0.5] (b6);
%\path (7.north) -- (7.south east) coordinate[pos=0.5] (a7);
%\path (7.south) -- (7.south west) coordinate[pos=0.5] (b7);
\draw[->] (0) to node {} (1);
\draw[->] (a1) to node {\footnotesize$\beta SZ$} (b1);
\path (1.east) -- (1.south east) coordinate[pos=0.5] (a2);
\path (2.west) -- (2.south west) coordinate[pos=0.5] (b2);
\draw[->] (a2) to[swap] node {\footnotesize$\delta S$} (b2);
\draw[->] (3) to node{} (5);
\draw[->] (2) to node{} (4);
\draw[->] (2) to node{\footnotesize $\alpha\lambda E$} (3);
%\draw[->] (1) to[in=135,out=45] node{\footnotesize$\zeta S$} (6);
\draw[->] (1) -- +(0,1cm) -| (6);
\node[above=1cm] at ($(1)!0.5!(6)$){\footnotesize$\zeta S$};
\draw[->] ([xshift=-0.3cm]6.south) -- +(0,-1cm) node[below]{\footnotesize$\delta V$};
\draw[->] ([xshift=0.3cm]6.south) -- +(0,-1cm) node[below]{\footnotesize$\beta VZ$};
\end{tikzpicture}
\end{document}
Something likes this. The solution changes/modifies the last 3 lines. Also some labels are changes to meet the drawing on article. As to the coloring of each block, try the following
fill=cyan!30!white, fill=red!30!white, fill=green!30!white
Code
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{babel,positioning,shapes,calc}
\begin{document}
\begin{tikzpicture}
\tikzset{node distance=2.3cm, auto}
\node (0) {\footnotesize$\pi (S+V)$};
\node (1) [right of=0, xshift = -0.5cm, shape=rectangle,draw=black, fill=cyan] {$S$};
\node (2) [right of=1, shape=rectangle,draw=black, fill=white] {$E$};
\node (3) [right of=2, shape = rectangle, draw = black, fill = red] {$Z$};
\node (4) [below of=2, yshift=1cm] {\footnotesize$(1-\alpha)\chi E$};
\node (5) [below of=3, yshift=1cm] {\footnotesize$\gamma (S+ V)Z$};
\node (6) [right of = 3, draw = black, fill = green] {$V$};
\node (7) [below of=6, shape = rectangle, yshift=1cm, text = white] {$V$};
\path (1.east) -- (1.north east) coordinate[pos=0.5] (a1);
\path (2.west) -- (2.north west) coordinate[pos=0.5] (b1);
\path (6.south) -- (6.south east) coordinate[pos=0.5] (a6);
\path (6.south) -- (6.south west) coordinate[pos=0.5] (b6);
\path (7.north) -- (7.south east) coordinate[pos=0.5] (a7);
\path (7.south) -- (7.south west) coordinate[pos=0.5] (b7);
\draw[->] (0) to node {} (1);
\draw[->] (a1) to node {\footnotesize$\beta SZ$} (b1);
\path (1.east) -- (1.south east) coordinate[pos=0.5] (a2);
\path (2.west) -- (2.south west) coordinate[pos=0.5] (b2);
\draw[->] (a2) to[swap] node {\footnotesize$\delta S$} (b2);
\draw[->] (3) to node{} (5);
\draw[->] (2) to node{} (4);
\draw[->] (2) to node{\footnotesize $\alpha\lambda E$} (3);
%\draw[->] (1) to[in=135,out=45] node{\footnotesize$\zeta S$} (6);
\draw[->] (1) -- +(0,1cm) -| (6);
\node[above=1cm] at ($(1)!0.5!(6)$){\footnotesize$\zeta S$};
\draw[->] (a6) -- (a7) node[below]{\footnotesize$\delta V$};
\draw[->] (b6) -- (b7)node[below]{\footnotesize$\beta VZ$};
\end{tikzpicture}
\end{document}
A PSTricks solution:
\documentclass{article}
\usepackage{pstricks}
\begin{document}
\begin{pspicture}(-2.28,-1.82)(7,1.84) % found manually
{\psset{fillstyle = solid} \Large
\psframe[fillcolor = blue!30](0,0)(1,1)
\rput(0.5,0.5){$S$}
\psframe(2,0)(3,1)
\rput(2.5,0.5){$E$}
\psframe[fillcolor = red!30](4,0)(5,1)
\rput(4.5,0.5){$Z$}
\psframe[fillcolor = green!30](6,0)(7,1)
\rput(6.5,0.5){$V$}}
{\psset{arrows = ->, labelsep = 2.5pt} \footnotesize
\psline(-1,0.5)(0,0.5)
\psline(!1 2 3 div)(!2 2 3 div)
\psline(!1 1 3 div)(!2 1 3 div)
\psline(3,0.5)(4,0.5)
\psline(2.5,0)(2.5,-1)
\psline(4.5,0)(4.5,-1)
\psline(0.5,1)(0.5,1.5)(6.5,1.5)(6.5,1)
\psline(!19 3 div 0)(!19 3 div -1)
\psline(!20 3 div 0)(!20 3 div -1.5)
\uput[180](-1,0.5){$\pi(S + V)$}
\uput[90](!1.5 2 3 div){$\beta SZ$}
\uput[270](!1.5 1 3 div){$\delta S$}
\uput[90](3.5,0.5){$\alpha\lambda E$}
\uput[270](2.5,-1){$(1 - \alpha)\chi E$}
\uput[270](4.5,-1){$\gamma(S + V)Z$}
\uput[90](3.5,1.5){$\zeta S$}
\uput[270](!19 3 div -1){$\delta V$}
\uput[270](!20 3 div -1.5){$\beta V{\mkern -2mu}Z$}}
\end{pspicture}
\end{document}
