Search results
Results from the WOW.Com Content Network
Cluster analysis or clustering is the task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some specific sense defined by the analyst) to each other than to those in other groups (clusters).
(top) Initial cluster assignment. (middle) The graph after the first step 2, in which (in order) the pink, green, yellow, red, black, white, and blue nodes were selected. (bottom) The graph after a second step 2, in which the green and white nodes were selected, with the order of the remaining nodes after that not important.
Automatic clustering algorithms are algorithms that can perform clustering without prior knowledge of data sets. In contrast with other cluster analysis techniques, automatic clustering algorithms can determine the optimal number of clusters even in the presence of noise and outlier points. [1] [needs context]
Much of the model-based clustering software is in the form of a publicly and freely available R package. Many of these are listed in the CRAN Task View on Cluster Analysis and Finite Mixture Models. [34] The most used such package is mclust, [35] [36] which is used to cluster continuous data and has been downloaded over 8 million times. [37]
Biclustering, block clustering, [1] [2] Co-clustering or two-mode clustering [3] [4] [5] is a data mining technique which allows simultaneous clustering of the rows and columns of a matrix. The term was first introduced by Boris Mirkin [ 6 ] to name a technique introduced many years earlier, [ 6 ] in 1972, by John A. Hartigan .
Complete-linkage clustering is one of several methods of agglomerative hierarchical clustering. At the beginning of the process, each element is in a cluster of its own. The clusters are then sequentially combined into larger clusters until all elements end up being in the same cluster. The method is also known as farthest neighbour clustering.
Two points p and q are density-connected if there is a point o such that both p and q are reachable from o. Density-connectedness is symmetric. A cluster then satisfies two properties: All points within the cluster are mutually density-connected. If a point is density-reachable from some point of the cluster, it is part of the cluster as well.
The average silhouette of the data is another useful criterion for assessing the natural number of clusters. The silhouette of a data instance is a measure of how closely it is matched to data within its cluster and how loosely it is matched to data of the neighboring cluster, i.e., the cluster whose average distance from the datum is lowest. [8]