How to find self loops and multiple relations between the same vertices?

Mar 16, 2011 at 2:54 PM


I am working on some data for citation analysis and co-authorship networks. The issue that I face is, if there are more than one articles by the same co-authors then NodeXL displays it just once. Is there a way to set this option so that NodeXL displays the actual count of relations between two different vertices?

The second part of my question is: how would it be done if there is a single author for an article?

Hope to hear back soon!


Mar 16, 2011 at 5:43 PM

If I understand correctly, your edges represent a co-authorship, some co-authors have co-authored more than one article, and you want the number of such articles to be displayed in the graph.  Here is one solution, assuming you don't mind merging edges:

1. Select NodeXL, Data, Prepare Data, Merge Duplicate Edges.  This will merge duplicate co-author edges into a single edge and add a new Edge Weight column to the Edges worksheet.

2. Select NodeXL, Visual Properties, Autofill Columns.

3. In the Edge Label row of the Autofill Columns dialog box, select Edge Weight for the "using the values in" column.

4. Select Autofill in the Autofill Columns dialog box.  This adds a label to each edge.  The edge label is a number that indicates the number of articles co-authored by the authors connected by the edge.

-- Tony

Mar 16, 2011 at 5:48 PM

On your second question, when there is a single author for an article, do you have a row for that article with the same author in Vertex 1 and Vertex 2?  If so, the above solution will show a "self-loop" edge for the author, but it won't show a number, because NodeXL doesn't show edge labels for self-loops.  But I can suggest an alternative solution if necessary.

-- Tony

Mar 16, 2011 at 7:41 PM

Thanks Tony the previous solution worked!

For the second part of my question, yes I have the same author appearing in Vertex1 and vertex2 for all those articles by a single author.

What alternate would you suggest?



Mar 16, 2011 at 9:45 PM
Edited Mar 16, 2011 at 10:30 PM

The alternative is to make the width of each merged edge proportional to the edge weight.  Thick edges would then represent multi-article co-authors.  To do this, use the Edge Width row instead of the Edge Label row in step 3 above.

When you do this, Autofill Columns fills the Width column on the Edges worksheet with the maximum range of possible edge widths -- from 1.0 to 10.0.  You might find that the widest edges are too wide for your taste.  If that's the case, then in the Autofill Column dialog box click the Options button to the right of Edge Width, then select Edge Width Options.  In the Edge Width Options dialog box, you can change the 1.0-to-10.0 edge width range to some other range: 1.0-to-4.0, for example.

There is nothing stopping you from using both the Edge Width AND the Edge Label rows in the Autofill Columns dialog box, in which case both the labels AND the edge widths will reflect the number of co-authored articles.  (Except for the self-loops, that is, which can't have labels.)

-- Tony