Initial thoughts on NodeXL NodeXL is a project from Microsoft and collaborators to bring some decent social network analysis tools to the masses - that is, the masses who have access to Microsoft Office. It's not supposed to be the most powerful thing on the planet, but functional for people who are comfortable in Excel and aren't comfortable either programming or using one of the other SNA tools (primarily UCInet and Pajek).

My very quick take
1) still a PITA to install and run (go ahead and get .net 3.5 sp1 first, reboot, then install it)
2) good idea - a lot of potential
3) easy to make attractive pictures - a lot more difficult to actually get the picture to show the information I want -- specifically, I can't seem to label the nodes (I can't get it to put the info that is in column a in the secondary label column for love nor money and I am Excel functional), nor size them by centrality measure (this is a very standard thing to do)
4) very nice that it sucks Pajek .net files in without issues (this was an old network I had sitting around)
5) it's nice you can click on a vertex in the spreadsheet and it will be highlighted on the graph
6) it's not good that changing the colors of the nodes actually triggers it to rearrange them (grrr)
7) apparently you can use equations to change colors and stuff - I haven't tried that yet.

Labels: sna

  ¶ 6:09 PM| (1) comments |cites (technorati) |

  IEEE eScience: My Slides

Slightly more information in an earlier post.
Paper available only upon request until I figure out the rules (just e-mail me) - it will probably be in Xplore in a couple of months.

Labels: IEEEeScience08, science blogging, sna

  ¶ 2:10 PM| (0) comments |cites (technorati) |

  Some notes for Pajek > R > iGraph These are mostly so I can find them again (argh)....
Install R, package iGraph, Pajek

In Pajek "locate" R:
tools > R > locate R ... look in c: > program files > R > R-2.7.1 > bin > Rgui.exe (your mileage and R version may vary)

Load your data into Pajek (with a .net, under networks click on the folder)
Do whatever manipulations in Pajek that you want to do (drop isolates, it's much easier in Pajek)
Tools > R > Send to R > Current network

If you had a version of R open, it will open another. No point in opening R first. When R opens, you'll have the information from pajek:
######################################
R called from Pajek
http://vlado.fmf.uni-lj.si/pub/networks/pajek/
Vladimir Batagelj & Andrej Mrvar
University of Ljubljana, Slovenia
-----------------------------------------------------------------------
The following networks/matrices read:
n1 : C:/Documents and Settings/...(1182)

Use objects() to get list of available objects
Use comment(?) to get information about selected object
Use savevector(v?,'???.vec') to save vector to Pajek input file
Use savematrix(n?,'???.net') to save matrix to Pajek input file (.MAT)
savematrix(n?,'???.net',2) to request a 2-mode matrix (.MAT)
Use savenetwork(n?,'???.net') to save matrix to Pajek input file (.NET)
savenetwork(n?,'???.net',2) to request a 2-mode network (.NET)
Use v?<-loadvector('???.vec') to load vector(s) from Pajek input file
Use n?<-loadmatrix('???.mat') to load matrix from Pajek input file
-----------------------------------------------------------------------

It's actually called n1 (yes, they say this, but...)

load the igraph package (packages > load)

You now have to make your adjacency matrix into a "graph"


then you can sort of cookbook from the igraph page.... use their models and their in-progress tutorial book

Oh and name everything you call, I just did the community detection and forgot to add the name<- in front of it

Labels: sna

  ¶ 3:36 PM| (0) comments |cites (technorati) |