Method and system for obtaining grading partition tree of dual-reverse furthest neighbors on road network
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A hierarchical partition tree, road network technology, applied in special data processing applications, instruments, electrical digital data processing, etc., can solve the problem of not strictly defining the convex hull, etc.
Inactive Publication Date: 2013-10-09
SHANGHAI JIAO TONG UNIV
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However, since the points on the road network have no direct relationship with the R-Tree index, and there is no strictly defined convex hull, these methods cannot be directly applied to the problems solved by the present invention
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Embodiment 1
[0069] The present invention provides a hierarchical partitioning tree method for obtaining the reverse farthest neighbor on the road network, including:
[0070] Step 1: If figure 1 As shown, for a certain node p on a given road network G and all nodes V on the road network G G , if there is a node q on the road network G, the road network distance between q and p ||q-p|| is not less than p to V G Among them, the distance ||p'-p|| of any point p', then define q as p relative to V G The farthest neighbor of , denoted as fn(p,V G );
[0071] Step 2: For all nodes V on the given road network G G and a query set Q on the road network G, define that the complex inverse farthest neighbors of q∈Q are all V G The set of points whose middle distance q is farther than all other points in Q, that is, BRFN(q,Q,V G )={p|p∈V G ,fn(p,Q)=q};
[0072] Step 3: select a plurality of nodes L on the road network G as landmarks, and use the Dijkstra algorithm to pre-calculate the distance ...
Embodiment 2
[0096] The present invention also provides another hierarchical partition tree system for obtaining the reverse farthest neighbor on the road network, including:
[0097] Module 1, for a certain node p on a given road network G and all nodes V on the road network G G , if there is a node q on the road network G, the road network distance between q and p ||q-p|| is not less than p to V G Among them, the distance ||p'-p|| of any point p', then define q as p relative to V G The farthest neighbor of , denoted as fn(p,V G );
[0098] Module 2, for all nodes V on a given road network G G and a query set Q on the road network G, define that the complex inverse farthest neighbors of q∈Q are all V G The set of points whose middle distance q is farther than all other points in Q, that is, BRFN(q,Q,V G )={p|p∈V G ,fn(p,Q)=q};
[0099] Module 3 is used to select multiple nodes L on the road network G as landmarks, and use the Dijkstra algorithm to pre-calculate the distance from ea...
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Abstract
The invention provides a method and system for obtaining a grading partition tree of dual-reverse furthest neighbors on a road network. The method includes the steps of, as for the road network G and a certain inquiry set Q, building a furthest Voronoi graph of the road network G with respect to the inquiry set Q, defining a furthest Voronoi region of a certain inquiry node q, belonging to the Q, on the furthest Voronoi graph to be the nodes fvc (q,Q), enabling the equation fn(p,Q)=q to be met, namely enabling all the nodes p contained by the fvc(q,Q) to regard the q as the furthest neighbors of the nodes p relative to the Q, enabling BRFN(q, Q, VG) to equal the fvc(q,Q), in order to obtain the fvc(q,Q), firstly building a set S containing potential solutions of all nodes VG on the road network G, every time taking out a node q' from the other nodes of the Q, dividing the S into two parts according to the distance between each potential solution in the set S and the q and the distance between each potential solution in the set S and the q', deleting the part close to the inquiry node q from the S until all the other nodes q' of the Q are taken out, and enabling the final part which is not deleted in the furthest Voronoi graph to be the fvc(q,Q), wherein the potential solutions are certain nodes on the road network G, and single reverse neighbors of an inquired node can be rapidly searched on the road network.
Description
technical field [0001] The invention relates to a hierarchical partition tree method and system for obtaining the reverse farthest neighbors on the road network. Background technique [0002] A spatial database (spatial database) refers to a database that provides spatial data types (spatial database type, SDT) and corresponding implementation support (see Document 1: Güting R H. An introduction to spatial database systems [J]. The VLDB Journal, 1994 , 3(4):357-399). With the increasing development of mobile computing and cloud computing, the application of spatial correlation algorithms is increasing. Proximity query includes Nearest Neighbor query, Reverse Nearest Neighbor query, Reverse Furthest Neighbor query, etc. It is one of the most common types of spatial database queries . The present invention focuses on the reverse furthest neighbor (RFN) query on the road network database, that is, given a set of data sets P and query sets Q on the road network, we hope to ob...
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