cutree {stats}

Cut a Tree into Groups of Data

Description

Cuts a tree, e.g., as resulting from hclust, into several groups either by specifying the desired number(s) of groups or the cut height(s).

Usage

cutree(tree, k = NULL, h = NULL)

Arguments

tree

a tree as produced by hclust. cutree() only expects a list with components merge, height, and labels, of appropriate content each.

k

an integer scalar or vector with the desired number of groups

h

numeric scalar or vector with heights where the tree should be cut.

At least one of k or h must be specified, k overrides h if both are given.

Details

Cutting trees at a given height is only possible for ultrametric trees (with monotone clustering heights).

Value

cutree returns a vector with group memberships if k or h are scalar, otherwise a matrix with group memberships is returned where each column corresponds to the elements of k or h, respectively (which are also used as column names).

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

hclust, dendrogram for cutting trees themselves.

Examples

hc <- hclust(dist(USArrests))

cutree(hc, k = 1:5) #k = 1 is trivial
cutree(hc, h = 250)

## Compare the 2 and 4 grouping:
g24 <- cutree(hc, k = c(2,4))
table(grp2 = g24[,"2"], grp4 = g24[,"4"])