JanusGraph Geo Predicates¶
JanusGraph provides APIs to query the dataset based on Geometric Point. The configuration to setup Geometric data types on which queries can be done, is dependeng on the Indexing backend being used.
For creating Geo index, refer to JanusGraph Geo Mapping docs.
Available Geo Predicates¶
The Geo Predicate provides the following 4 types of predicates for queries the data.
While, in current release only geoContains and geoWithin is implemented.
Contributions are invited for development of other following Geo Predicates.
- geoDisjoint
- geoIntersect
geoContains¶
This Predicate is part of Geo package.
geoContains is used to query a scenario where we want to test weather a Geometric
object contains another.
Hence, for example, since New Delhi is capital of India, the query
GeoShape(India) contains GeoShape(New Delhi) holds true.
For scope of example, we have added a point named arcadia with co-ordinates 7.58 21.50 and radius 5km (Circle). For reference, see the docs about GeoShapes (Note how latitude and longitude are reversed).
from janusgraph_python.core.datatypes.GeoShape import GeoShape
from janusgraph_python.core.attribute import Geo
arcadia = GeoShape.Circle(21.50, 7.58, 5)
==> CIRCLE(lat: 7.58, lon: 21.5, r: 5)
edgeAdded = g.V(birds).as_("to").V(hercules).addE("battled").property("time", 290).
property("place", arcadia).to("to").next()
==> e[63hf6j-3bs-9hx-36g][4312-battled->4120]
shape = GeoShape.Circle(21.50, 7.58, 2)
herculesBattledWith = g.V().has("name", "hercules").outE().has("place", Geo.geoContains(shape)).next()
==> e[63hee3-3bs-9hx-36g][4312-battled->4120]
geoWithin¶
This Predicate is part of Geo package.
geoWithin is used to query a scenario where we want to test weather a Geometric
object is within another.
Hence, for example, since New Delhi is capital of India, the query
GeoShape(New Delhi) contains GeoShape(India) holds true.
Note the difference in usage of GeoContains and GeoWithin with respect to the GeoShape object being used to query.
from janusgraph_python.core.datatypes.GeoShape import GeoShape
from janusgraph_python.core.attribute import Geo
arcadia = GeoShape.Circle(21.50, 7.58, 5)
==> CIRCLE(lat: 7.58, lon: 21.5, r: 5)
edgeAdded = g.V(birds).as_("to").V(hercules).addE("battled").property("time", 290).property("place", arcadia).to("to").next()
==> e[63hf6j-3bs-9hx-36g][4312-battled->4120]
shape = GeoShape.Circle(21.50, 7.58, 100)
edges = g.V().has("name", "hercules").outE().has("place", Geo.geoWithin(shape)).next()
==> e[63hee3-3bs-9hx-36g][4312-battled->4120]