blockmodeling (version 0.1.9)

nkpartitions: Functions for listing all possible partitions or just cunting the number of them.

Description

The function nkpartitions lists all possible partitions of n objects in to k clusters. The function nkpar only gives the number of such partitions.

Usage

nkpartitions(n, k, exact = TRUE, print = FALSE)
nkpar(n, k)

Arguments

n

Number of units/objects

k

Number of clusters/groups

exact

Search for partitions with exactly k or at most k clusters

print

print results as they are found?

Value

The matrix or number of possible partitions.

Examples

# NOT RUN {
n<-8 #if larger, the number of partitions increases dramaticaly,
     #as does if we increase the number of clusters
net<-matrix(NA,ncol=n,nrow=n)
clu<-rep(1:2,times=c(3,5))
tclu<-table(clu)
net[clu==1,clu==1]<-rnorm(n=tclu[1]*tclu[1],mean=0,sd=1)
net[clu==1,clu==2]<-rnorm(n=tclu[1]*tclu[2],mean=4,sd=1)
net[clu==2,clu==1]<-rnorm(n=tclu[2]*tclu[1],mean=0,sd=1)
net[clu==2,clu==2]<-rnorm(n=tclu[2]*tclu[2],mean=0,sd=1)

#computation of criterion function with the correct partition
nkpar(n=n, k=length(tclu)) #computing the number of partitions
all.par<-nkpartitions(n=n, k=length(tclu)) #forming the partitions
all.par<-lapply(apply(all.par,1,list),function(x)x[[1]])
# to make a list out of the matrix
res<-check.these.par(M=net,partitions=all.par,approach="ss",blocks="com")
plot(res) #we get the original partition
# }