dissimilarity.object Dissimilarity Matrix Object
Description
Objects of class "dissimilarity" representing the dissimilarity matrix of a dataset.
Value
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):
. |
GENERATION
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.
METHODS
The "dissimilarity" class has methods for the following generic functions: print, summary.
See Also
daisy, dist, pam, clara, fanny, agnes, diana.
Copyright (©) 1999–2012 R Foundation for Statistical Computing.
Licensed under the GNU General Public License.