This library provides Python functions for hierarchical clustering. It generates hierarchical clusters from distance matrices or from vector data. Part of this module is intended to replace the functions linkage, single, complete, average, weighted, centroid, median, ward in the module scipy.cluster.hierarchy with the same functionality but much faster algorithms. Moreover, the function linkage_vector provides memory-efficient clustering for vector data. The interface is very similar to MATLAB’s Statistics Toolbox API to make code easier to port from MATLAB to Python/NumPy. The core implementation of this library is in C++ for efficiency.