Fastcluster 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.

WWW: http://danifold.net/fastcluster.html