3.8 KiB
@brief The _shortestPath function returns all shortest paths of a graph.
graph._shortestPath(startVertexExample, endVertexExample, options)
This function determines all shortest paths in a graph. The function accepts an id, an example, a list of examples or even an empty example as parameter for start and end vertex. 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.
@PARAMS
@PARAM{startVertexExample, object, optional} An example for the desired start Vertices (see Definition of examples).
@PARAM{endVertexExample, object, optional} An example for the desired end Vertices (see Definition of examples).
@PARAM{options, object, optional} An object containing options, see below:
- 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.
@EXAMPLES
A route planner example, shortest path from all german to all french cities:
@EXAMPLE_ARANGOSH_OUTPUT{generalGraphModuleShortestPaths1} var examples = require("@arangodb/graph-examples/example-graph.js"); var g = examples.loadGraph("routeplanner"); | g._shortestPath({}, {}, {weight : 'distance', endVertexCollectionRestriction : 'frenchCity', startVertexCollectionRestriction : 'germanCity'}); ~ examples.dropGraph("routeplanner"); @END_EXAMPLE_ARANGOSH_OUTPUT
A route planner example, shortest path from Hamburg and Cologne to Lyon:
@EXAMPLE_ARANGOSH_OUTPUT{generalGraphModuleShortestPaths2} var examples = require("@arangodb/graph-examples/example-graph.js"); var g = examples.loadGraph("routeplanner"); | g._shortestPath([{_id: 'germanCity/Cologne'},{_id: 'germanCity/Munich'}], 'frenchCity/Lyon', {weight : 'distance'}); ~ examples.dropGraph("routeplanner"); @END_EXAMPLE_ARANGOSH_OUTPUT