cluster: dissimilarity.object – R documentation

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cluster

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): A Asymmetric binary S Symmetric binary N Nominal (factor) O Ordinal (ordered factor) I Interval scaled (numeric) T raTio to be log transformed (positive numeric) .

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.

Martin Maechler [aut, cre] (<https://orcid.org/0000-0002-8685-9910>), Peter Rousseeuw [aut] (Fortran original, <https://orcid.org/0000-0002-3807-5353>), Anja Struyf [aut] (S original), Mia Hubert [aut] (S original, <https://orcid.org/0000-0001-6398-4850>), Kurt Hornik [trl, ctb] (port to R; maintenance(1999-2000), <https://orcid.org/0000-0003-4198-9911>), Matthias Studer [ctb], Pierre Roudier [ctb], Juan Gonzalez [ctb], Kamil Kozlowski [ctb], Erich Schubert [ctb] (fastpam options for pam(), <https://orcid.org/0000-0001-9143-4880>), Keefe Murphy [ctb] (volume.ellipsoid({d >= 3}))

Initial release

2021-04-16