Hi, i would recommend to use the igraph package, i think it can be done with the others as well, but i don't know them too much.
If your ids are numeric, be sure that the first id is zero. Then create a matrix of your data with the parentid in the first column and the id in the second and omit the NA's. So you need something like this: from1 to1 from2 to2 . . . from1 -> from to1 is the first directed edge, from2 -> to2 the second, etc. If you have that (say in variable 'el') then it is pretty straightforward. If you have 'N' different ids library(igraph) g <- graph(t(el), n=N) cl1 <- clusters(g, mode="weak") cl2 <- clusters(g, mode="strong") These calculate weakly and strongly connected components in your graph. Strongly connected means that in has to be possible to reach each node from each other node via a directed path. In the weakly connected case, a single undirected path between nodes is enough to be in the same component. In cl1 you have cl1$membership which contains the id of its cluster for every node (cluster ids start with zero) and cl1$csize contains the sizes of the clusters. The same applies to cl2. Hope this helps, Gabor On Thu, May 04, 2006 at 06:02:14PM -0400, [EMAIL PROTECTED] wrote: > Hello, > > I have data with 1500+ observations. Each observation has two > attributes _id_, a self identifier, and _parentid_, identifying a > single association with a previous observation. The value of > _parentid_ can either be the _id_ value of that single associated > observation or NA. Different observations can be associated with > the same previous observation and share the same value for > _parentid_. In this way, these 1500+ observations form a directed > graph made up of several disconnected clusters (of various sizes) > and several isolates. I need to identify these disconnected > clusters of two or more observations. I have been trying to figure > out how to use the network, sna, and kinship packages, but, without > little time before finals to read the relevant literature, I am > desperate for some helpful advice. > > Thank you in advance-- > > John > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html -- Csardi Gabor <[EMAIL PROTECTED]> MTA RMKI, ELTE TTK ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
