rect.hclust               package:mva               R Documentation

Draw Rectangles Around Hierarchical Clusters

Description:

     Draws rectangles around the branches of a dendrogram highlighting
     the corresponding clusters. First the dendrogram is cut at a
     certain level, then a rectangle is drawn around selected branches.

Usage:

     rect.hclust(tree, k = NULL, which = NULL, x = NULL, h = NULL,
                 border = 2, cluster = NULL)

Arguments:

    tree: an object of the type produced by `hclust'.

    k, h: Scalar. Cut the dendrogram such that either exactly `k'
          clusters are produced or by cutting at height `h'.

which, x: A vector selecting the clusters around which a rectangle
          should be drawn. `which' seleccts clusters by number (from
          left to right in the tree), `x' selects clusters containing
          the respective horizontal coordinates. Default is `which =
          1:k'.

  border: Vector with border colors for the rectangles.

 cluster: Optional vector with cluster memberships as returned by
          `cutree(hclust.obj, k = k)', can be specified for efficiency
          if already computed.

Value:

     (Invisibly) returns a list where each element contains a vector of
     data points contained in the respective cluster.

See Also:

     `hclust', `identify.hclust'.

Examples:

     library(mva)
     data(USArrests)
     hca <- hclust(dist(USArrests))
     plot(hca)
     rect.hclust(hca, k=3, border="red")
     x <- rect.hclust(hca, h=50, which=c(2,7), border=3:4)
     x

