1

Here is my flowchart and I want to add labels L1,L2, and L3 to the bent arrows. Though following code worked (ref: Adding a label to a bent arrow in TikZ)

\draw [arrow] (b8.south)++(.3,0) |- ++(0,-1.5) -| node[pos=0.225,above] {L3} (b7);

But it requires manual adjustment of position. Is there an efficient way to work around this issue?

enter image description here

1

You can use the auto and midway option for the node to place the label automatically:

\draw [arrow] (b8.south)++(.3,0) |- ++(0,-1.5) -| node[midway,auto] {L3} (b7);

EDIT: How to include L1 and L2 nodes. We replace auto by the positioning of the node we want: either left or right. There can also be a way to define the right level at which |- arrows meet. Or you can extract the y-component of b11 node using the let operation, which I have done here. You will need to use the calc library.

\documentclass[tikz]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}

\begin{document}
\begin{tikzpicture}
\tikzset{every node/.append style={inner sep=0pt,outer sep=0pt,
minimum height=1cm,minimum width=2cm,draw},
Lnode/.style={outer sep=#1,inner sep=1mm,
minimum size=0pt,draw=green,fill=green,text=red}};
%
\node[draw=red,ultra thick] (b8) at (5cm,0) {B8};
\node[minimum width=0pt,inner sep=1mm] (b9) at (2,0) {B9};
\node[draw=blue,ultra thick] (b10) at (-1cm,0) {B10};
\node (b11) at (2cm,-2cm) {B11};
% Using let operation to extract the exact coordinates for B-nodes
\draw[->] let \p1=(b11.center),\p2=(b10.center) in
(b10.south) -- (\x2,\y1) node[Lnode=1mm,midway,left]{L1} -- (b11.west);
\draw[<-] let \p1=(b11.center),\p2=(b8.center) in
(b8.south) -- (\x2,\y1) node[Lnode=1mm,midway,right]{L2} -- (b11.east);
\draw[->] (b8) -- (b9); \draw[->] (b9) -- (b10);
\end{tikzpicture}
\end{document}

Result: Automaton node labelling

  • Your solution puts L3 at right place. Can L1 and L2 be done in a similar manner? – NAASI Mar 4 '16 at 20:59
  • Definitely, just have to include these options for those nodes. SinceB the L1, L2, L3 are different in node style to B8,B9, etc., we make a different node style for them. This time we do not use auto, but choose where to place the L-nodes: either left or right, as preferred. I have updated my answer to include L1 and L2. – smike Mar 5 '16 at 14:41

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