K-Means clustering generates a specific number of disjoint, flat
(non-hierarchical) clusters. It is well suited to generating globular
clusters. The K-Means method is numerical, unsupervised, non-deterministic
and iterative.

Quality Threshold (QT) clustering algorithm

The Euclidean distance (or Euclidean metric) is the "ordinary" (i.e.
straight-line) distance between two points in Euclidean space.

The Levenshtein distance is a metric for measuring the amount of difference
between two sequences (i.e. an edit distance). The Levenshtein distance
between two strings is defined as the minimum number of edits needed to
transform one string into the other, with the allowable edit operations
being insertion, deletion, or substitution of a single character.

Pearson's correlation coefficient is the covariance of the two variables
divided by the product of their standard deviations, and is commonly
represented by the Greek letter ρ (rho).

The Spearman correlation coefficient is defined as the Pearson correlation
coefficient between the ranked variables.