[Tex/LaTex] Tikz add arrows to multiple segments of a `\draw` command

graphicstikz-pgf

I'm drawing an org chart and I'd like to have arrows pointing to each of the nodes I do so. I'm also lazily using a single draw command to draw a line from each of the nodes as the last part of my process. Is there some way that I can specify an [->] going to C and B but not to hub1 in the example I've shown without drawing each line individually?

\documentclass[10pt]{article}
\usepackage{tikz}
\usetikzlibrary{calc,positioning}
\tikzstyle{a}=[rectangle,draw]

\begin{document}
\begin{tikzpicture}
\node [a] (A) at (0,0) {A};
\node [a,below=1cm of A] (B) {B};
\node [a,left=1cm of B] (C) {C};
\node [a,right=1cm of B] (D) {D};
\node [below=0.25cm of A] (hub1) {};
\draw [->] (A.south) -- (hub1.south) -| (C.north) (hub1.south) -- (B.north) (hub1.south) -| (D.north);

\end{tikzpicture}
\end{document}

editing on from @texenthusiast comment below I've tried using a \foreach loop to edit this, but now the arrow for B points the wrong way. Any thoughts?

\documentclass[a6]{minimal}
\usepackage{tikz}
\usetikzlibrary{calc,positioning}
\tikzstyle{a}=[rectangle,draw]

\begin{document}
\begin{tikzpicture}
\node [a] (A) at (0,0) {A};
\node [a,below=1cm of A] (B) {B};
\node [a,left=1cm of B] (C) {C};
\node [a,right=1cm of B] (D) {D};
\coordinate [below=0.6cm of A] (hub1) {};
\foreach \a/\b/\c in {C/east/0.1cm,B/north/0,D/west/-0.1cm}
\draw [->] (hub1) -| ($(\a.\b)+(\c,0)$) -- (\a.\b);
\end{tikzpicture}
\end{document}

Best Answer

If you want to have the arrow to appear on every single path part, you should use the edge option which default behaviour is a line to (--) and does work similar to a to only that in a construct like

\path (A) edge (B)
          edge (C);

the second line is drawn from (A) to (C) and not from (B) to (C) as in

\draw (A) to (B) to (C);

Of course the linebreak isn’t part of TikZ’ syntax but only highlights this fact.

In the code below I have declared (hub1) as a coordinate so to not have a invisible node with an border. The path operator -| is usually not available for edge but can be easily declared in a to path.

The utilisation of such an auxiliary coordinate like (hub1) is not a bad idea in general. Though, if you often need paths like those from (A) to (C) you can declare relatively easily a |-| to path.
Instead of two -- you can also use one -- and one -| path operator. This only affects node positioning. (If needed one can also “hack” a real |-| path operator that can be used like -- or -| where you can place nodes on the whole path without manually constructing it. A similar thing was done in another answer of mine.

Note that I have explicitly avoided to use \p1 and \p2 as they would possibly overwrite the coordinates declared on a user-level.

Code

\documentclass[tikz]{standalone}
\usetikzlibrary{positioning,calc}
\tikzset{
  a/.style={rectangle,draw},
  -|/.style={to path={-| (\tikztotarget) \tikztonodes}},
  |-|/.style={to path={
      let \p{qrr@to@start}=(\tikztostart), \p{qrr@to@target}=(\tikztotarget) in
      -- (\x{qrr@to@start},.5*\y{qrr@to@start}+.5*\y{qrr@to@target}) -- (\x{qrr@to@target},.5*\y{qrr@to@start}+.5*\y{qrr@to@target}) \tikztonodes -- (\tikztotarget)
    }
  }
}

\begin{document}
\begin{tikzpicture}
\node [a] at (0,0)       (A) {A};
\node [a,below=1cm of A] (B) {B};
\node [a, left=1cm of B] (C) {C};
\node [a,right=1cm of B] (D) {D};
\coordinate [below=0.5cm of A] (hub1) {};
\path [->] (A)    edge     (B)
           (hub1) edge[-|] (C)
                  edge[-|] (D);

\end{tikzpicture}

\begin{tikzpicture}
\node [a] at (0,0)       (A) {A};
\node [a,below=1cm of A] (B) {B};
\node [a, left=1cm of B] (C) {C};
\node [a,right=1cm of B] (D) {D};
\path[every edge/.append style={|-|}, ->] (A) edge (B)
                                              edge (C)
                                              edge (D);

\end{tikzpicture}
\end{document}

Output

enter image description here

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