Figure 1.

The SWIFT strategy for primary clustering, splitting, and merging. (A) Demonstration of the three steps in SWIFT to cluster the data using the EM algorithm; split multimodal clusters; and merge overlapping clusters. One dimension is shown for clarity—SWIFT actually operates in all dimensions simultaneously. (B) Merging proceeds sequentially, testing all possible overlapping pairs by the KL divergence and merging the most similar pair only if the merged result is unimodal. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]