One vertex in multiple groups and multiple edges between vertex?

Aug 13, 2012 at 8:43 PM

I am trying to use NodeXL to identify the interfaces for a piece of machinery, its basically the same as a social network but replace people with an engine, transmission, fuel system, etc...

Each system can have several interfaces, physical, information, energy transfer, material exchange and information exchange. The engine has a physical interface with transmission and also has an energy transfer. And you can create several network views with the systems (vertex) grouped in different ways. For example you can group by system owner or group by physical location on machine.

Two questions

1. Is it possible for a single vertex to be assigned to two different groups? I plan on using an excel function to determine which group should be visible, only one set of groups will be visible at any given time. Not trying to create a sub-group to a group but rather to manage two distinct sets of groups so that we can view our network in two different ways. I tried to create two sets of groups and control the visibility via an IF statement (if user enters Owner a particular set of groups are set to visible and all others to not visible, for example) but this does not seem to work. My hunch is this is not working because the vertex is assigned a unique ID and even when assigned to different groups this same ID is used to identify the vertex.

2. Is it possible to create multiple interfaces between systems (multiple edges between two vertex) and have the edges seperated (not on top of each other)? In the example above the engine and transmission have two interfaces so in a context diagram you would see two lines connecting these two systems, one for the physical interface (a solid line) and one for energy transfer (a dotted line). I tried this in nodexl and the two edges end up directly on top of each other, which of course will not work. Currently I am working around this by using the method described in question one above, but in this case it works. I am able to contol the visibiliy of edges using an IF statement, so if user enters Physical the diagram displays the Physical interfaces, if they enter Information only the information interfaces are displayed. This works fine but it would be nice to see all interfaces at one time.

Sorry for the long post, thanks in advance for any advice.





Aug 13, 2012 at 9:34 PM

1. In NodeXL a vertex may be in just one group at a time.  However, the Group by Vertex Attribute feature lets you select which attribute to group by and there can be many different attributes in your data set.

2. Parallel edges get written on top of each other in the current version of NodeXL.  We are exploring better edge display options.  One quick fix is to make different edges different widths and different transparency (opacity) so that big, wide edges can be seen through to narrower darker edges.


Aug 14, 2012 at 8:11 PM

1. Thanks. This is a much better solution than what I was trying. However, I noticed that after I run the Group By Attribute tool my vertices visual properties change in the diagram even though the settings shown in the spreadsheet have not changed. For example, I had a vertex set to use an image and the image was displaying appropriatly but after using Group By Vertex the diagram now displays that vertex as a blue disc and I cannnot revert back so that the images display correctly. Is this a known issue?

2. Thanks for the information and the suggested work around. We will explore our options, I am sure we will come up with something that works.


 Thanks for your help...

Aug 14, 2012 at 10:44 PM

1. You are very welcome!  Groups and vertices both have attributes.  By default when a vertex is placed in a group we use the group level attributes for all the vertex attributes.  This is not always what you want.  When this is not what you want, when you want vertex level attributes to display rather than group level attributes, you can change the settings in the NodeXL>Analysis>Groups>Group Options>`.


Aug 15, 2012 at 7:32 PM

Great! I tried that and it worked perfect.  I think I have spreadsheet set up and not its just a matter of associating the vertices with one another to produce the map.


Thanks for your help.