scikit-learn/scikit-learn — pull request #391 by jmetzen (2011-10-12 07:49:11+00:00)
Title: Fixed bug in updating structure matrix in ward_tree algorithm

Change: Formerly, when merging two clusters, the merge was not connected to all other clusters the two childs had been connected to. This could result in raised Exceptions when connected components of the graph become unconnected. Now, the connections are propagated up through the ward tree during merging such that connected components remain always connected.