sna (version 2.4)

centralgraph: Find the Central Graph of a Labeled Graph Stack

Description

Returns the central graph of a set of labeled graphs, i.e. that graph in which i->j iff i->j in >=50% of the graphs within the set. If normalize==TRUE, then the value of the i,jth edge is given as the proportion of graphs in which i->j.

Usage

centralgraph(dat, normalize=FALSE)

Arguments

dat

one or more input graphs.

normalize

boolean indicating whether the results should be normalized. The result of this is the "mean matrix". By default, normalize==FALSE.

Value

A matrix containing the central graph (or mean matrix)

Details

The central graph of a set of graphs S is that graph C which minimizes the sum of Hamming distances between C and G in S. As such, it turns out (for the dichotomous case, at least), to be analogous to both the mean and median for sets of graphs. The central graph is useful in a variety of contexts; see the references below for more details.

References

Banks, D.L., and Carley, K.M. (1994). ``Metric Inference for Social Networks.'' Journal of Classification, 11(1), 121-49.

See Also

hdist

Examples

# NOT RUN {
#Generate some random graphs
dat<-rgraph(10,5)
#Find the central graph
cg<-centralgraph(dat)
#Plot the central graph
gplot(cg)
#Now, look at the mean matrix
cg<-centralgraph(dat,normalize=TRUE)
print(cg)
# }