con.comp {fpc}

Connectivity components of an undirected graph

Description

Computes the connectivity components of an undirected graph from a matrix giving the edges.

Usage

con.comp(comat)

Arguments

comat

a symmetric logical or 0-1 matrix, where comat[i,j]=TRUE means that there is an edge between vertices i and j. The diagonal is ignored.

Details

The "depth-first search" algorithm of Cormen, Leiserson and Rivest (1990, p. 477) is used.

Value

An integer vector, giving the number of the connectivity component for each vertice.

Author(s)

Christian Hennig [e-mail] https://www.unibo.it/sitoweb/christian.hennig/en/

References

Cormen, T. H., Leiserson, C. E. and Rivest, R. L. (1990), Introduction to Algorithms, Cambridge: MIT Press.

See Also

hclust, cutree for cutted single linkage trees (often equivalent).

Examples

  set.seed(1000)
  x <- rnorm(20)
  m <- matrix(0,nrow=20,ncol=20)
  for(i in 1:20)
    for(j in 1:20)
      m[i,j] <- abs(x[i]-x[j])
  d <- m<0.2
  cc <- con.comp(d)
  max(cc) # number of connectivity components
  plot(x,cc)
  # The same should be produced by
  # cutree(hclust(as.dist(m),method="single"),h=0.2).