4.9 KiB
The GRAPH_SHORTEST_PATH function returns all shortest paths of a graph.
GRAPH_SHORTEST_PATH (graphName, startVertexExample, endVertexExample, options)
This function determines all shortest paths in a graph identified by graphName. If one wants to call this function to receive nearly all shortest paths for a graph the option algorithm should be set to Floyd-Warshall to increase performance. If no algorithm is provided in the options the function chooses the appropriate one (either Floyd-Warshall or Dijkstra) according to its parameters. The length of a path is by default the amount of edges from one start vertex to an end vertex. The option weight allows the user to define an edge attribute representing the length.
The complexity of the function is described here.
Parameters
- graphName : The name of the graph as a string.
- startVertexExample : An example for the desired start Vertices (see example).
- endVertexExample : An example for the desired end Vertices (see example).
- options (optional) : An object containing the following options:
- direction : The direction of the edges as a string. Possible values are outbound, inbound and any (default).
- edgeCollectionRestriction : One or multiple edge collection names. Only edges from these collections will be considered for the path.
- startVertexCollectionRestriction : One or multiple vertex collection names. Only vertices from these collections will be considered as start vertex of a path.
- endVertexCollectionRestriction : One or multiple vertex collection names. Only vertices from these collections will be considered as end vertex of a path.
- edgeExamples : A filter example for the edges in the shortest paths (see example).
- algorithm : The algorithm to calculate the shortest paths. If both start and end vertex examples are empty Floyd-Warshall is used, otherwise the default is Dijkstra.
- weight : The name of the attribute of the edges containing the length as a string.
- defaultWeight : Only used with the option weight. If an edge does not have the attribute named as defined in option weight this default is used as length. If no default is supplied the default would be positive Infinity so the path could not be calculated.
- stopAtFirstMatch : Only useful if targetVertices is an example that matches to more than one vertex. If so only the shortest path to the closest of these target vertices is returned. This flag is of special use if you have target pattern and you want to know which vertex with this pattern is matched first.
- includeData : Triggers if only _id's are returned (false, default) or if data is included for all objects as well (true) This will modify the content of vertex, path.vertices and path.edges.
NOTE: Since version 2.6 we have included a new optional parameter includeData. This parameter triggers if the result contains the real data object true or it just includes the _id values false. The default value is false as it yields performance benefits.
@EXAMPLES
A route planner example, shortest distance from all german to all french cities:
@EXAMPLE_ARANGOSH_OUTPUT{generalGraphShortestPaths1} var examples = require("@arangodb/graph-examples/example-graph.js"); var g = examples.loadGraph("routeplanner"); | db._query("FOR e IN GRAPH_SHORTEST_PATH(" | + "'routeplanner', {}, {}, {" + | "weight : 'distance', endVertexCollectionRestriction : 'frenchCity', " + | "includeData: true, " + | "startVertexCollectionRestriction : 'germanCity'}) RETURN [e.startVertex, e.vertex._id, " + | "e.distance, LENGTH(e.paths)]" ).toArray(); ~ examples.dropGraph("routeplanner"); @END_EXAMPLE_ARANGOSH_OUTPUT
A route planner example, shortest distance from Hamburg and Cologne to Lyon:
@EXAMPLE_ARANGOSH_OUTPUT{generalGraphShortestPaths2} var examples = require("@arangodb/graph-examples/example-graph.js"); var g = examples.loadGraph("routeplanner"); | db._query("FOR e IN GRAPH_SHORTEST_PATH(" | +"'routeplanner', [{_id: 'germanCity/Cologne'},{_id: 'germanCity/Munich'}], " + | "'frenchCity/Lyon', " + | "{weight : 'distance'}) RETURN [e.startVertex, e.vertex, e.distance, LENGTH(e.paths)]" ).toArray(); ~ examples.dropGraph("routeplanner"); @END_EXAMPLE_ARANGOSH_OUTPUT