an indexing structure for knn search for moving objects on road networks
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NW.vedge
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vtree_build.cpp
vtree_knn_demo.cpp

README.md

V-Tree: Efficient kNN Search on Moving Objects with Road-Network Constraints

This project consists of implement of V-Tree, which designed to support kNN search on moving objects with road-network constraints.

[Dependence]

[METIS] is required before you run the program.it is used to partition the graph. Thus, before compile our code, you must install METIS in your linux system. METIS link & download: http://glaros.dtc.umn.edu/gkhome/metis/metis/overview

get metics from
http://glaros.dtc.umn.edu/gkhome/metis/metis/download

##[Example of Install METIS]

wget http://glaros.dtc.umn.edu/gkhome/fetch/sw/metis/metis-5.1.0.tar.gz
gunzip metis-5.x.y.tar.gz
tar -xvf metis-5.x.y.tar
cd metics-5.x.y
make config
make
make install

#[Compile]

Simple build the file is make.

make 

The manual compile is : g++ -O3 vtree_build.cpp -lmetis -o vtree_build g++ -O3 vtree_knn_demo.cpp -lmetis -o vtree_knn_demo

Beware the linking issue, in our case, we use "g++ ... -lmetis" If it is not working, you can try "g++ ... -L///YOUR_METIS_LIB_PATH" Make sure "metis.h" is in your default include(.h) directory.

#[Usage]

1.Build a vtree index. ./vtree_build ./input_edge_file ./output_file 2.Load VTree and run KNN test use ./vtree_knn_demo ./VTree_file $K(int) $car_percent(int) $change_percent(int) $query_per_update' k means the number of k neighborhoods car_percent is the number of running vehicles on the road network change_percent means the percent of vehicles change to the other vertex between each query. query_per_update means the query number in between two updates

Some annotations were written among the code.

####[Example]

./vtree_build NW.vedge NW.vtree
./vtree_knn_demo NW.vtree 10 0.01 0.002 6

##[Input file format]

The edge file is consist of two pars. First line is the overall information of the graph. The other line is the detail edge information.

1089933 2545844    //The first line of the input file shows the number of vertices and edges.
1 2 1157            //The first row is the origin, the second row is destination, the third row is the weight of the edge.
1 6 5413
2 1 1157
2 3 2394
2 7 3857
...

The VTree input is directed graph. If an undirected graph is used, it also support that. !The parameter RevE needs to be true when the undirected graph is used. !If the number of graph is not In our code, we did not assert the input graph is connected graph But connected graph must be guaranteed before METIS partition the graph Hence, it is suggested you have to pre-process the input road network for your own dataset

##[Some useful parameter of the source code]

Partition_Part // the fanout of the vtree

Naive_Split_Limit // the max number of the leaf node, which is τ+1 in the article.

NWFIX // if the number of edge starts from 0 Set NWFIX = true, otherwise set it to false.


For better understanding of our code, we provide example(Northwest USA Road Network dataset) File use: (Note the file input format) NW.vedge (graph edge file) simple run is run

bash run_demo.sh

Licence

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.