Distance between edges and nodes in graphviz

Question

How do I configure the distance between edges and nodes (red), i.e. the outer shape of a node(blue)?

Answer 1

Here is a technique that you can consider that avoids the need to create a custom node shape. There may be some matters of taste that you may need to address further in order to get exactly what you want.

The advantage of this technique, using HTML-like labels, is that varying the space inside and outside the rectangle becomes a simple matter of changing the inner number of points (here 4) and outer number of points (here 16) respectively.

digraph {

node [shape=none]

O [label=<
<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="16" CELLPADDING="4">
<TR><TD WIDTH="70">\N</TD></TR>
</TABLE>
>]

{a,b,c,d} -> O

}

Result:

You can change the BORDER and CELLBORDER parameters to show or hide the rectangles. You can adjust their thicknesses although only in multiples of 1 point. I have used the WIDTH parameter to force a width-to-height ratio that causes the aligning of all the arrow tips. Otherwise some of the tips would meet the sides of the invisible outer rectangle.

Answer 2

Like the other answer said, this isn't really an easy feat. Using a combination of height, width, fixedsize, labelloc, and margin node parameters, you can probably get any desired effect you'd like. Margin is best is you're looking to expand that distance, but to minimize it you need to use the other params. For example, this graph would have the arrowheads almost touching the 'O' node's text.

digraph {
  node [shape="none" width=.2 height=.2 fixedsize="true" labelloc="top"];

  a -> O;
  b -> O;
  c -> O;
  d -> O;
}

Alternatively, if you really want to put in effort, you could create a custom node shape, and do whatever you'd like to it.