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The filtering algorithm uses k-d trees to speed up each k-means step. [35] Some methods attempt to speed up each k-means step using the triangle inequality. [22] [23] [24] [36] [25] Escape local optima by swapping points between clusters. [9] The Spherical k-means clustering algorithm is suitable for textual data. [37]
In data mining, k-means++ [1] [2] is an algorithm for choosing the initial values (or "seeds") for the k-means clustering algorithm. It was proposed in 2007 by David Arthur and Sergei Vassilvitskii, as an approximation algorithm for the NP-hard k-means problem—a way of avoiding the sometimes poor clusterings found by the standard k-means algorithm.
In applied mathematics, k-SVD is a dictionary learning algorithm for creating a dictionary for sparse representations, via a singular value decomposition approach. k-SVD is a generalization of the k-means clustering method, and it works by iteratively alternating between sparse coding the input data based on the current dictionary, and updating the atoms in the dictionary to better fit the data.
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]
The algorithm unwinds the recursion of the tree, performing the following steps at each node: If the current node is closer than the current best, then it becomes the current best. The algorithm checks whether there could be any points on the other side of the splitting plane that are closer to the search point than the current best.
Another method that modifies the k-means algorithm for automatically choosing the optimal number of clusters is the G-means algorithm. It was developed from the hypothesis that a subset of the data follows a Gaussian distribution. Thus, k is increased until each k-means center's data is Gaussian. This algorithm only requires the standard ...
K-means clustering is an algorithm for grouping genes or samples based on pattern into K groups. Grouping is done by minimizing the sum of the squares of distances between the data and the corresponding cluster centroid. Thus the purpose of K-means clustering is to classify data based on similar expression. [20]
This image is part of an example of the K-means algorithm. This is the first step, where the points and centroids are randomly placed. Date: 26 July 2007: Source: Own ...