Data Structure for Multilayer N‐Dimensional Data Using Hierarchical Structure

Abstract Data such as vectors, points and symbols of maps and facilities location maps are classified into layers and managed according to such attributes as roads, houses, and facilities. In editing a diagram, range searchings and neighborhood searching frequently are made, where the objects of search are the data in a number of layers. When such multidimensional data classified into layers (called multilayer data) are managed by the conventional multidimensional data structure, a problem occurs in that the retrieval efficiency varies greatly depending on the number of considered layers. This paper proposes the ML structure (multi‐layered structure), which is a new managing structure for the multilayer data based on a tree structure. In ML structure, the node structure is extended so that data can be stored not only in the terminal node of the tree but also in the internal node. A layer management mechanism is added to each node. It is arranged that the data of the layer with small number of data are placed close to the root of the tree structure. As a result, a satisfactory performance with small variation in the retrieval efficiency is realized, even if a range searching is made for a particular layer, or for a number of layers. This paper describes the construction of ML structure, method of data management, and searching. It is shown by experiment that the data management and searching by ML structure is effective for the multilayer data.