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From: | Chris Watson |
Subject: | Re: [igraph] triad census |
Date: | Tue, 26 May 2015 12:04:06 -0400 |
Further to my previous e-mail, this is how I found the number of triangles:conn <- array (dim = c(vcount(el.13), vcount(el.13), vcount(el.13)))for (i in 1:length(Successor)){for (j in 1:length(Successor[[i]])) {for (k in (j+1):(length(Successor[[i]]))){conn[i,j,(k-1)] <- ifelse(length(Successor[[i]]) < 2, NA,ifelse(k > length(Successor[[i]]), NA,ifelse(V(el.13)[Successor[[i]][j]]==V(el.13)[Successor[[i]][k]],NA,are.connected(el.13, V(el.13)[Successor[[i]][j]], V(el.13)[Successor[[i]][k]]))))}}}So transitivity, as defined previously would be:trans <- sum(conn, na.rm = T)/tripletsCould someone more experienced tell me if this is ok and the reason of the differences with triad.census in the number of triplets of the form B <- A -> C ???Thanks!On Tue, May 26, 2015 at 10:41 AM, Tadaishi Yatabe-Rodriguez <address@hidden> wrote:Hi all,I'm trying to calculate transitivity of the form B <- A -> C, where also B->C in a directed graph. For this I counted all the neighbors looping over each vertex using the function neighbors(graph[i], mode='out'). Then I counted the number of neighbors using the function length. Finally I get the number of possible triplets for each vertex using combinatorial, i.e. choose(number.neihgbors, 2) and I got the number of triplets of the form B <- A -> C for each vertex. When I added them all and then compare with the results from triad census for the same kind of triplets results didn't match. Any idea why? Here's the code##Successors of ASuccessor=list()for (i in 1:vcount(el.13)){Successor[[i]] <- neighbors(el.13, v=V(el.13)[i], mode = "out")}### Clustering of the form B <- A -> C, where also B->Cn.succ <- sapply(Successor, FUN=length)trip <- choose(n.succ, 2)triplets <- sum(trip)Thanks!--Tadaishi YatabeDVM, MPVM, PhD (C)Center for Animal Disease Modeling and Surveillance (CADMS)Department of Medicine and EpidemiologySchool of Veterinary MedicineUniversity of California Davis--Tadaishi YatabeDVM, MPVM, PhD (C)Center for Animal Disease Modeling and Surveillance (CADMS)Department of Medicine and EpidemiologySchool of Veterinary MedicineUniversity of California Davis
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