Data depth is a statistical method which models data distribution in terms of center-outward ranking rather than density or linear ranking. While there are a lot of academic interests, its applications are hampered by the lack of a method which is both robust and efficient. This paper introduces
Most density-based clustering algorithms suffer from large density variations among clusters. This paper proposes a new measure called Neighbourhood Contrast (NC) as a better alternative to density in detecting clusters. The proposed NC admits all local density maxima, regardless of their densities, to have similar NC values. Due to this unique property, NC is a better means to detect clusters in a dataset with large density variations among clusters. We provide two applications of NC. First, replacing density with NC in the current state-of-the-art clustering procedure DP leads to significantly improved clustering performance. Second, we devise a new clustering algorithm called Neighbourhood Contrast Clustering (NCC) which does not require density or distance calculations, and therefore has a linear time complexity in terms of dataset size. Our empirical evaluation shows that both NC-based methods outperform density-based methods including the current state-of-the-art.