1. Graph Visualization CSC4170 Web Intelligence and Social Computing Tutorial 2 Tutor: Tom Chao Zhou Email: czhou@cse.cuhk.edu.hkczhou@cse.cuhk.edu.hk

2. Outline Background Graph Visualization Tools Case Study: Pajek Q & A

3. Background Visualization is a technique to graphically represent sets of data. When data is large or abstract, visualization can help make the data easier to read or understand.

4. Visualization Tools  Pajek: http://pajek.imfm.si/doku.php?id=pajekhttp://pajek.imfm.si/doku.php?id=pajek  UCINET: http://www.analytictech.com/downloaduc6.htmhttp://www.analytictech.com/downloaduc6.htm  Netdraw: http://www.analytictech.com/Netdraw/netdraw.htmhttp://www.analytictech.com/Netdraw/netdraw.htm  Stocnet: http://stat.gamma.rug.nl/stocnet/http://stat.gamma.rug.nl/stocnet/  Manyeyes: http://manyeyes.alphaworks.ibm.com/manyeyes/http://manyeyes.alphaworks.ibm.com/manyeyes/  …

5. Case Study: Pajek  Pajek:  Program for Large Network Analysis.  Download page:  http://pajek.imfm.si/doku.php?id=download http://pajek.imfm.si/doku.php?id=download  Manual:  http://vlado.fmf.uni-lj.si/pub/networks/pajek/doc/pajekMan.pdf http://vlado.fmf.uni-lj.si/pub/networks/pajek/doc/pajekMan.pdf

6. Case Study: Pajek Draw “Network” with Pajek:  List of neighbours (Arcslist/Edgeslist) (unweighted graph)  Pairs of lines (Arcs/Eges) (weighted graph)  Matrix

7. Case Study: Pajek List of neighbours (Arcslist/Edgeslist) *Vertices 5 1 “a” 2 “b” 3 “c” 4 “d” 5 “e” *Arcslist 1 2 4 2 3 3 1 4 4 5 *Edgeslist 1 5  Words, starting with *, must be written in first column of the line.  Definition of vertices followed after that – to each vertex we give a label.  using *Arcslist, a list of directed lines from selected vertices are declared.  *Edgeslist, declares a list of undirected lines.  No empty lines are allowed.

8. Case Study: Pajek 1, read the.net file 1, draw the network

9. Case Study: Pajek Pairs of lines (Arcs/Edges) *Vertices 5 1 "a" 2 "b" 3 "c" 4 "d" 5 "e" *Arcs 1 2 1 1 4 1 2 3 2 3 1 1 3 4 2 4 5 1 *Edges 1 5 1  Every arc/edge is defined separately in new line – initial and terminal vertex are given.  Directed lines are defined using *Arcs, undirected lines are defined using *Edges, the third number in rows defining the weight.

10. Case Study: Pajek Matrix *Vertices 5 1 "a" 2 "b" 3 "c" 4 "d" 5 "e" *Matrix 0 1 0 1 1 0 0 2 0 0 1 0 0 2 0 0 0 0 0 1 1 0 0 0 0 In this format directed lines are given in the matrix form (*Matrix). We can transform bidirected arcs to edges.

11. Case Study: Pajek Export to bmp, eps…

12. Case Study: Pajek Computing indegree and outdegree using Pajek: double click Partitions

13. Case Study: Pajek Graph and Digraph Glossary example:  Derived from Bill Cherowitzo's Graph and Digraph Glossary. http://www-math.cudenver.edu/~wcherowi/courses/m4408/glossary.html  An arc (X,Y) from term X to term Y exists in the network iff in the Graph and Digraph Glossary the term Y is used to describe the meaning of term X.

15. Questions?