Class SpatialStrategy

The SpatialStrategy encapsulates an approach to indexing and searching based on shapes.

Different implementations will support different features. A strategy should document these common elements:

  • Can it index more than one shape per field?
  • What types of shapes can be indexed?
  • What types of query shapes can be used?
  • What types of query operations are supported? This might vary per shape.
  • Does it use the FieldCache, or some other type of cache? When?
If a strategy only supports certain shapes at index or query time, then in general it will throw an exception if given an incompatible one. It will not be coerced into compatibility.

Note that a SpatialStrategy is not involved with the Lucene stored field values of shapes, which is immaterial to indexing and search.

Thread-safe.

@lucene.experimental

Inheritance
System.Object
SpatialStrategy
PrefixTreeStrategy
SerializedDVStrategy
PointVectorStrategy
Inherited Members
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
Assembly: Lucene.Net.Spatial.dll
Syntax
[Serializable]
public abstract class SpatialStrategy

Constructors

Name Description
SpatialStrategy(SpatialContext, String)

Constructs the spatial strategy with its mandatory arguments.

Fields

Name Description
m_ctx

Properties

Name Description
FieldName

The name of the field or the prefix of them if there are multiple fields needed internally.
SpatialContext

Methods

Name Description
MakeDistanceValueSource(IPoint)

See MakeDistanceValueSource(IPoint, Double) called with a multiplier of 1.0 (i.e. units of degrees).
MakeDistanceValueSource(IPoint, Double)

Make a ValueSource returning the distance between the center of the indexed shape and queryPoint. If there are multiple indexed shapes then the closest one is chosen. The result is multiplied by multiplier, which conveniently is used to get the desired units.
MakeFilter(SpatialArgs)

Make a Filter based principally on SpatialOperation and IShape from the supplied args.

If a subclasses implements MakeQuery(SpatialArgs) then this method could be simply:

return new QueryWrapperFilter(MakeQuery(args).Query);
MakeQuery(SpatialArgs)

Make a Query based principally on SpatialOperation and IShape from the supplied args. The default implementation is

return new ConstantScoreQuery(MakeFilter(args));
MakeRecipDistanceValueSource(IShape)

Returns a ValueSource with values ranging from 1 to 0, depending inversely on the distance from MakeDistanceValueSource(IPoint). The formula is c / (d + c) where 'd' is the distance and 'c' is one tenth the distance to the farthest edge from the center. Thus the scores will be 1 for indexed points at the center of the query shape and as low as ~0.1 at its furthest edges.
ToString()

Extension Methods