Ordering Grids to Identify the Clustering Structure

Almost all of the well-known clustering algorithms require input parameters while these parameters may be difficult to be determined. OPTICS (Ordering Points To Identify the Clustering Structure Cluster Structure) is a primary semi-clustering method to visualize the data structure and to determine the input parameters of a given clustering algorithm. However, OPTICS has too high complexity O(n 2 logn) to be applied to any large dataset of n data. In this paper, we present a new semi-clustering method by partitioning data space into a number of grids and Ordering all Grids To Identify the Clustering Structure (OGTICS). Accordingly, the new method is called OGTICS. The OGTICS has only linear complexity O(n) and thus is much faster than OPTICS. Consequently, the OGTICS can be applied to very large dataset.