Desenhando setas de diferentes bordas do nó/caixa de decisão

Question

Sou novo no tikz e não entendo como desenhar linhas originadas de todas as bordas de uma caixa de decisão para outros nós.

No diagrama abaixo , como posso especificar o ponto de origem de uma seta? Por exemplo, quero desenhar uma seta da parte inferior da Decisão1 até a borda esquerda da Decisão2, mas não consigo descobrir como.

Meu código:

\documentclass{article}
\usepackage{tikz}
\usepackage{fixltx2e}
\usetikzlibrary{shapes,arrows}
\usetikzlibrary{positioning}
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}%
%%%>
\begin{document}
\pagestyle{empty}

% Define block styles
\tikzstyle{decision} = [diamond, draw, fill=blue!20, 
    text width=6.5em, text badly centered, node distance=3cm, inner sep=0pt]
\tikzstyle{block} = [rectangle, draw, fill=blue!20, 
    text width=10em, text centered, rounded corners, minimum height=4em]
\tikzstyle{mycircle} = [circle, thick, draw=orange, minimum height=4mm]

\tikzstyle{line} = [draw, -latex']
\tikzstyle{cloud} = [draw, ellipse,fill=red!20, node distance=3cm,
    minimum height=2em]

\begin{tikzpicture}[align=center,node distance = 2cm, auto]
    % Place nodes
    \node [block] (init) {Read system data};
    \node [block, right of=init, node distance=6cm] (trip) {Trip};

    \node [block, below of=init, node distance=2.7cm] (setloadavg)
             {Set average loading level to L\textsubscript{avg}=[0.8,0.9,1,1.1]};
    \node [decision, right of=setloadavg, node distance=6cm] (decision2) {Decision2};
    \node [block, right of=decision2, node distance=3cm] (stop1) {Stop};

    \node [block, below of=setloadavg, node distance=3cm] (setk) {Set K};
    \node [decision, right of=setk, node distance=6cm] (decision3) {Decision3};
    \node [mycircle, right of=decision3, node distance=4cm] (circle1) {1};

    \node [block, below of=setk, node distance=2cm] (startsim)
        {Start simulation (run 1) to generate cascade data, K=0};
    \node [block, right of=startsim, node distance=6cm] (increment) {Increment};
    \node [mycircle, left of=startsim, node distance=4cm] (circle2) {2};

    \node [block, below of=startsim, node distance=3cm] (setloadlevel) {Set Load level};
    \node [decision, right of=setloadlevel, node distance=6cm] (decision4) {Decision4};
    \node [mycircle, right of=decision4, node distance=4cm] (circle3) {2};

    \node [block, below of=setloadlevel, node distance=3cm] (runloadflow) {Run load flow};
    \node [block, right of=runloadflow, node distance=6cm] (stop2) {stop};

    \node [decision, below of=runloadflow, node distance=3cm] (decision1) {Decision1};
    \node [mycircle, left of=decision1, node distance=4cm] (circle2) {1};


    % Draw edges
    \path [line] (init) -- (setloadavg);
    \path [line] (setloadavg) -- (setk);
    \path [line] (setk) -- (startsim);
    \path [line] (startsim) -- (setloadlevel);
    %\path [line] (startsim) -- (circle2);
    \path [line] (setloadlevel) -- (runloadflow);
    \path [line] (runloadflow) -- (decision1);
    \path [line] (decision1) -- node [near start] {Yes} +(3,0) |-  (trip);


\end{tikzpicture}
\end{document}

Eu apreciaria alguma explicação sobre a solução e dicas para documentação, se possível.

Obrigado

Answer 1

Uma possibilidade:

\documentclass{article}
\usepackage{tikz}
\usepackage{fixltx2e}
\usetikzlibrary{shapes,arrows}
\usetikzlibrary{positioning}
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}%
%%%>
\begin{document}
\pagestyle{empty}

% Define block styles
\tikzstyle{decision} = [diamond, draw, fill=blue!20,
    text width=6.5em, text badly centered, node distance=3cm, inner sep=0pt]
\tikzstyle{block} = [rectangle, draw, fill=blue!20,
    text width=10em, text centered, rounded corners, minimum height=4em]
\tikzstyle{mycircle} = [circle, thick, draw=orange, minimum height=4mm]

\tikzstyle{line} = [draw, -latex']
\tikzstyle{cloud} = [draw, ellipse,fill=red!20, node distance=3cm,
    minimum height=2em]

\begin{tikzpicture}[align=center,node distance = 2cm, auto]
    % Place nodes
    \node [block] (init) {Read system data};
    \node [block, right of=init, node distance=6cm] (trip) {Trip};

    \node [block, below of=init, node distance=2.7cm] (setloadavg)
             {Set average loading level to L\textsubscript{avg}=[0.8,0.9,1,1.1]};
    \node [decision, right of=setloadavg, node distance=6cm] (decision2) {Decision2};
    \node [block, right of=decision2, node distance=3cm] (stop1) {Stop};

    \node [block, below of=setloadavg, node distance=3cm] (setk) {Set K};
    \node [decision, right of=setk, node distance=6cm] (decision3) {Decision3};
    \node [mycircle, right of=decision3, node distance=4cm] (circle1) {1};

    \node [block, below of=setk, node distance=2cm] (startsim)
        {Start simulation (run 1) to generate cascade data, K=0};
    \node [block, right of=startsim, node distance=6cm] (increment) {Increment};
    \node [mycircle, left of=startsim, node distance=4cm] (circle2) {2};

    \node [block, below of=startsim, node distance=3cm] (setloadlevel) {Set Load level};
    \node [decision, right of=setloadlevel, node distance=6cm] (decision4) {Decision4};
    \node [mycircle, right of=decision4, node distance=4cm] (circle3) {2};

    \node [block, below of=setloadlevel, node distance=3cm] (runloadflow) {Run load flow};
    \node [block, right of=runloadflow, node distance=6cm] (stop2) {stop};

    \node [decision, below of=runloadflow, node distance=3cm] (decision1) {Decision1};
    \node [mycircle, left of=decision1, node distance=4cm] (circle2) {1};


    % Draw edges
    \path [line] (init) -- (setloadavg);
    \path [line] (setloadavg) -- (setk);
    \path [line] (setk) -- (startsim);
    \path [line] (startsim) -- (setloadlevel);
    %\path [line] (startsim) -- (circle2);
    \path [line] (setloadlevel) -- (runloadflow);
    \path [line] (runloadflow) -- (decision1);
    \path [line] (decision1) -- node [near start] {Yes} +(3,0) coordinate (my coord) |-  (trip);
    \path [line] (decision1.south) -- +(0,-20pt) -| ([xshift=5pt, yshift=-5pt]my coord) |- (decision2.west);


\end{tikzpicture}
\end{document}

Ao colocar uma coordenada na linha anterior, podemos navegar em torno dela ao colocar o caminho da nova seta. .southe .westsão âncoras dos nós decision1e decision2, correspondentes ao ponto de saída e entrada que você deseja. Usar o xshift...,yshift...garante que a linha fique próxima da anterior, sem ficar bem em cima dela.

Observe que parte da sua sintaxe está desatualizada. Por exemplo, você deve usar \tikzsetem vez de \tikzstyle.