compute_tightness {mappeR} | R Documentation |
Compute dispersion of a single cluster
Description
Compute dispersion of a single cluster
Usage
compute_tightness(dists, cluster)
Arguments
dists |
A distance matrix for points in the cluster. |
cluster |
A list containing named vectors, whose names are data point names and whose values are cluster labels |
Details
This method computes a measure of cluster dispersion. It finds the medoid of the input data set and returns the average distance to the medoid. Formally, we say the tightness \tau
of a cluster C
is given by
\tau(C) = \dfrac{1}{\left(|C|-1\right)}\displaystyle\sum_{i}\text{dist}(x_i, x_j)
where
x_j = \text{arg}\,\min\limits_{x_j\in C}\, \sum_{x_i \in C, i\neq j}\text{dist}(x_i, x_j)
A smaller value indicates a tighter cluster based on this metric.
Value
A real number in [0,1]
representing a measure of dispersion of a cluster.
[Package mappeR version 1.3.0 Index]