The structure and objects contained in PULS, an object returned from the PULS() function and used as the input in other functions in the package.

Value

frame

Data frame in the form of a tibble::tibble() representing a tree structure with one row for each node. The columns include:

number

Index of the node. Depth of a node can be derived by number %/% 2.

var

Name of the variable used in the split at a node or "<leaf>" if it is a leaf node.

n

Cluster size, the number of observations in that cluster.

wt

Weights of observations. Unusable. Saved for future use.

inertia

Inertia value of the cluster at that node.

bipartsplitrow

Position of the next split row in the data set (that position will belong to left node (smaller)).

bipartsplitcol

Position of the next split variable in the data set.

inertiadel

Proportion of inertia value of the cluster at that node to the inertia of the root.

medoid

Position of the data point regarded as the medoid of its cluster.

loc

y-coordinate of the splitting node to facilitate showing on the tree. See plot.PULS() for details.

inertia_explained

Percent inertia explained as described in Chavent (2007). It is 1 - (sum(current inertia)/inertial[1]).

alt

Indicator of an alternative cut yielding the same reduction in inertia at that split.

membership

Vector of the same length as the number of rows in the data, containing the value of frame$number corresponding to the leaf node that an observation falls into.

dist

Distance matrix calculated using the method indicated in distmethod argument of PULS().

terms

Vector of subregion names in the data that were used to split.

medoids

Named vector of positions of the data points regarded as medoids of clusters.

alt

Indicator of having an alternate splitting route occurred when splitting.

References

  • Chavent, M., Lechevallier, Y., & Briant, O. (2007). DIVCLUS-T: A monothetic divisive hierarchical clustering method. Computational Statistics & Data Analysis, 52(2), 687-701. doi: 10.1016/j.csda.2007.03.013 .

See also