Graph topology in Orthogonal Layout

Question

I would like to ask you some questions about the Orthogonal Layout and how nodes are displayed in this configuration.

I do no not understand why I obtain two different results when I apply the orthogonal layout without grouping nodes (left picture) and with groups of nodes which are interconnected among each other (right picture).

 

What I wish to achieve is a configuration similar to the left picture but with the two groups of orange nodes, having their relative chains of yellow nodes connected in straight and parallel lines. Why do some chains of edges take other directions which make them cross other lines and go round the rectangles of the groups? Is this maybe due to the size of the groups?

Abstracting from the first question, the overall layout I am trying to obtain is the one from the left picture below: grouped nodes at the sides of the rectangle from which chains of nodes depart in straight lines (as a drawing of an electronic integrated circuit), either with these chains ending up in other rectangular groups or not. I saw that when I apply the orthogonal layout to my network, I mostly obtain something similar to the right picture below, where there are some regions in which nodes are all intricated and  organised in a maze-like manner.

 

Do you know some tools or commands I can employ to improve my graph and get close to the electronic chip shape I showed you above?

Thank you in advance!

Answer 1

The Orthogonal Layout uses a pretty complex optimization algorithm and generally does not produce the desired parallel and straight-line result for chains. 

Your upper left example shows a special case where the Layout handles each chain component independently, which usually leads to straight parallel chains. However, if some chain nodes are placed within a group, the Layout can no longer apply this specific optimization strategy. Hence, unfortunately, the Orthogonal Layout is probably not the right choice here.

I recommend trying out the Hierarchic Layout, which should yield better results if the chains are directed (e.g., the edges connecting the chain nodes all point downwards). For the attached drawing, which resembles your example graph, I used the default settings of the Hierarchic Layout with "Grouping, Layering Strategy" set to "Layout Groups" and "Grouping, Compact Layers" unchecked. Of course, you may omit the target arrows, in which case you also must uncheck "Edges, Arrows define Edge Direction."