An efficient method for batch updates in OPTICS cluster ordering

Abstract

DBSCAN is one of the popular density-based clustering algorithms, but requires re-clustering the entire data when the input parameters are changed. OPTICS overcomes this limitation. In this paper, we propose a batch-wise incremental OPTICS algorithm which performs efficient insertion and deletion of a batch of points in a hierarchical cluster ordering, which is the output of OPTICS. Only a couple of algorithms are available in the literature on incremental versions of OPTICS. This can be attributed to the sequential access patterns of OPTICS. The existing incremental algorithms address the problem of incrementally updating the hierarchical cluster ordering for point-wise insertion/deletion, but these algorithms are only good for infrequent updates. The proposed incremental OPTICS algorithm performs batch-wise insertions/deletions and is suitable for frequent updates. It produces exactly the same hierarchical cluster ordering as that of classical OPTICS. Real datasets have been used for experimental evaluation of the proposed algorithm and results show remarkable performance improvement over the classical and other existing incremental OPTICS algorithms.