Agglomerative Hierarchical Clustering
Agglomerative hierarchical clustering is a widely used unsupervised machine learning technique aiming to build a hierarchy of clusters by iteratively merging data points or groups based on similarity measures. Current research focuses on improving its efficiency for high-dimensional data, particularly through integration with dimensionality reduction techniques like KPCA and the development of novel linkage methods based on ordered weighted averaging or dot products to enhance cluster recovery and avoid dendrogram inversions. This versatile method finds applications across diverse fields, including biomedical data analysis for disease subtyping, financial crime detection, spam email classification, and even animal pose recognition, demonstrating its broad utility in exploratory data analysis and pattern discovery.