Example ERGM (dyadic cov)

example_ergm.R

###########
# Example
##########

library(igraph)

actors <- data.frame(name=c("Alice", "Bob", "Cecil", "David",
                            "Esmeralda"),
                     age=c(48,33,45,34,21),
                     gender=c("F","M","F","M","F"))
relations <- data.frame(from=c("Bob", "Cecil", "Cecil", "David",
                               "David", "Esmeralda", "Alice"),
                        to=c("Alice", "Bob", "Alice", "Alice", "Bob", "Alice", "Bob"),
                        same.dept=c(TRUE,FALSE,TRUE,TRUE,FALSE,TRUE, TRUE), 
                        distance=c(3,1,4,5,6,4,3))

g <- graph.data.frame(relations, directed=TRUE, vertices=actors)

get.data.frame(g, what="vertices")
get.data.frame(g, what="edges")

plot(g)

detach("package:igraph")
library(intergraph)

n <- asNetwork(g)
mat <- as.sociomatrix(n, attrname="distance")
isSymmetric(mat)
mat
smat <- symmetrize(mat)                         # requires package sna
smat

# ERGM
library(ergm)

m01 <- ergm(n ~ edges + mutual + dyadcov(smat))
summary(m01)

m02 <- ergm(n ~ edges + mutual + dyadcov(smat))
summary(m02)