dissimilarity.object {cluster}R Documentation

Dissimilarity Matrix Object


Objects of class "dissimilarity" representing the dissimilarity matrix of a dataset.


The dissimilarity matrix is symmetric, and hence its lower triangle (column wise) is represented as a vector to save storage space. If the object, is called do, and n the number of observations, i.e., n <- attr(do, "Size"), then for i < j <= n, the dissimilarity between (row) i and j is do[n*(i-1) - i*(i-1)/2 + j-i]. The length of the vector is n*(n-1)/2, i.e., of order n^2.
"dissimilarity" objects also inherit from class dist and can use dist methods, in particular, as.matrix, such that d(i,j) from above is just as.matrix(do)[i,j].
The object has the following attributes:

Size the number of observations in the dataset.
Metric the metric used for calculating the dissimilarities. Possible values are "euclidean", "manhattan", "mixed" (if variables of different types were present in the dataset), and "unspecified".
Labels optionally, contains the labels, if any, of the observations of the dataset.
NA.message optionally, if a dissimilarity could not be computed, because of too many missing values for some observations of the dataset.
Types when a mixed metric was used, the types for each variable as one-letter codes (as in the book, e.g. p.54):
Asymmetric binary
Symmetric binary
Nominal (factor)
Ordinal (ordered factor)
Interval scaled (numeric)
raTio to be log transformed (positive numeric)


daisy returns this class of objects. Also the functions pam, clara, fanny, agnes, and diana return a dissimilarity object, as one component of their return objects.


The "dissimilarity" class has methods for the following generic functions: print, summary.

See Also

daisy, dist, pam, clara, fanny, agnes, diana.

[Package cluster version 1.9.8 Index]