Hi,
I'm trying to do some basic social network analysis with igraph in R, but I'm new to R and haven't been able to find documentation on a couple basic things: I want to run igraph's community detection algorithms on a couple thousand small graphs but don't know how to automate igraph looking at multiple graphs described in a single csv file. My data look like something in ncol format, but with an additional column that has an ID for which graph the edge belongs in: Graph ID | Vertex1 | Vertex2 | weight 1 | Alice | Bob | 2 1 | Alice | Chris | 1 1 | Alice | Jane | 2 1 | Bob | Jane | 2 1 | Chris | Jane | 3 2 | Alice | Tom | 2 2 | Alice | Kate | 1 2 | Kate | Tom | 3 2 | Tom | Mike | 2 so on and so forth for about 2000 graph IDs, each with about 20-40 vertices. I've tried using the "split" command but it doesn't recognize my graph id: ("object 'graphid' not found)--this may just be because I don't know how to classify a column of a csv as an object. Ultimately, I want to run community detection on each graph separately--to look only at the edges when the graph identifier is 1, make calculations on that graph, then do it again for 2 and so forth. I suspect that this isn't related to igraph specifically--I just don't know the equivalent command in R for what in pseudo Stata code would read as: forvalues i of 1/N { temp_graph=subrows of the main csv file for which graphid==`i' cs`i' = leading.eigenvector.community.step(temp_graph) convert cs`i'$membership into a column in the original csv } I want the output to look something like: Graph ID | Vertex1 | Vertex2 | weight | Vertex 1 membership | Vertex 2 membership | # of communities in the graph 1 | Alice | Bob | 2 | A | B | 2 1 | Alice | Chris | 1 | A | B | 2 1 | Alice | Jane | 2 | A | B | 2 1 | Bob | Jane | 2 | B | B | 2 1 | Chris | Jane | 3 | B | B | 2 2 | Alice | Tom | 2 | A | B | 3 2 | Alice | Kate | 1 | A | C | 3 2 | Kate | Tom | 3 | C | B | 3 2 | Tom | Mike | 2 | B | C | 3 Here, the graphs are treated completely separately so that community A in graph 1 need not have anything to do with community A in graph 2. I would really appreciate any ideas you guys have. Thank you! Danielle [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.