sna (version 0.3)

is.isolate: Is Ego an Isolate?

Description

Returns TRUE iff ego is an isolate in graph g of dat.

Usage

is.isolate(dat, ego, g=1, diag=FALSE)

Arguments

dat

A graph or graph stack

ego

Index of the vertex (or a vector of vertices) to check

g

Which graph should be examined?

diag

Boolean indicating whether adjacency matrix diagonals (i.e., loops) contain meaningful data

Value

• A boolean value (or vector thereof) indicating isolate status

Details

In the valued case, any non-zero edge value is taken as sufficient to establish a tie.

References

Wasserman, S., and Faust, K. (1994). ``Social Network Analysis: Methods and Applications.'' Cambridge: Cambridge University Press.

West, D.B. (1996). Introduction to Graph Theory. Upper Saddle River, NJ: Prentice Hall.

See Also

isolates, addisolates

Examples

#Generate a test graph
g<-rgraph(20)
g[,4]<-0          #Create an isolate
g[4,]<-0

#Check for isolates
is.isolate(g,2)  #2 is almost surely not an isolate
is.isolate(g,4)  #4 is, by construction