Efficiently mining maximal l-reachability co-location patterns from spatial data sets

Abstract

A co-location pattern is a set of spatial features that are strongly correlated in space. However, some of these patterns could be neglected if the prevalence metrics are based solely on the clique (or star) relationship. Hence, the l-reachability co-location pattern is proposed by introducing the l-reachability clique where the members of each instance pair can be reachable to each other in a given step length l. Because the average size of l-reachability co-location patterns tends to be longer, maximal l-reachability co-location pattern mining is researched in this paper. First, some sparsification strategies are introduced to shorten star neighborhood lists of instances in an updated graph called the l-reachability neighbor relationship graph, and then, they are grouped by their corresponding patterns. Second, candidate maximal l-reachability co-location patterns are iteratively detected in a size-independent way on bi-graphs that contain group keys and their intersection sets. Third, the prevalence of each candidate maximal l-reachability co-location pattern is checked in a binary search way with a natural l-reachability clique called the ⌊l/2⌋-reachability neighborhood list. Finally, the effectiveness and efficiency of our model and algorithms are analyzed by extensive comparison experiments on synthetic and real-world spatial data sets.