C# Class Lucene.Net.Spatial.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

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Protected Properties

Property	Type	Description
ctx	Spatial4n.Core.Context.SpatialContext

Public Methods

Method	Description
CreateIndexableFields ( IShape shape ) : Lucene.Net.Documents.Field[]	Returns the IndexableField(s) from the shape that are to be added to the Document. These fields are expected to be marked as indexed and not stored. Note: If you want to store the shape as a string for retrieval in search results, you could add it like this: `document.Add(new StoredField(fieldName, ctx.ToString(shape)));` The particular string representation used doesn't matter to the Strategy since it doesn't use it.
MakeDistanceValueSource ( IPoint queryPoint ) : ValueSource	See MakeDistanceValueSource(IPoint, double) called with a multiplier of 1.0 (i.e. units of degrees).
MakeDistanceValueSource ( IPoint queryPoint, double multiplier ) : ValueSource	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 args ) : Filter	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 args ) : ConstantScoreQuery	Make a Query based principally on SpatialOperation and IShape from the supplied args. The default implementation is `return new ConstantScoreQuery(MakeFilter(args));`
MakeRecipDistanceValueSource ( IShape queryShape ) : ValueSource	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 ( ) : string

Protected Methods

Method	Description
SpatialStrategy ( SpatialContext ctx, string fieldName ) : Lucene.Net.Documents	Constructs the spatial strategy with its mandatory arguments.

Method Details

CreateIndexableFields() public abstract method

Returns the IndexableField(s) from the shape that are to be added to the Document. These fields are expected to be marked as indexed and not stored.

Note: If you want to store the shape as a string for retrieval in search results, you could add it like this: document.Add(new StoredField(fieldName, ctx.ToString(shape))); The particular string representation used doesn't matter to the Strategy since it doesn't use it.

if given a shape incompatible with the strategy

public abstract CreateIndexableFields ( IShape shape ) : Lucene.Net.Documents.Field[]
shape	IShape
return	Lucene.Net.Documents.Field[]

MakeDistanceValueSource() public method

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

public MakeDistanceValueSource ( IPoint queryPoint ) : ValueSource
queryPoint	IPoint
return	ValueSource

MakeDistanceValueSource() public abstract method

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.

public abstract MakeDistanceValueSource ( IPoint queryPoint, double multiplier ) : ValueSource
queryPoint	IPoint
multiplier	double
return	ValueSource

MakeFilter() public abstract method

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);

If the strategy does not support the shape in . If the strategy does not support the in .

public abstract MakeFilter ( SpatialArgs args ) : Filter
args	Lucene.Net.Spatial.Queries.SpatialArgs
return	Lucene.Net.Search.Filter

MakeQuery() public method

Make a Query based principally on SpatialOperation and IShape from the supplied args. The default implementation is return new ConstantScoreQuery(MakeFilter(args));

If the strategy does not support the shape in . If the strategy does not support the in .

public MakeQuery ( SpatialArgs args ) : ConstantScoreQuery
args	Lucene.Net.Spatial.Queries.SpatialArgs
return	Lucene.Net.Search.ConstantScoreQuery

MakeRecipDistanceValueSource() public method

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.

public MakeRecipDistanceValueSource ( IShape queryShape ) : ValueSource
queryShape	IShape
return	ValueSource

SpatialStrategy() protected method

Constructs the spatial strategy with its mandatory arguments.

protected SpatialStrategy ( SpatialContext ctx, string fieldName ) : Lucene.Net.Documents
ctx	Spatial4n.Core.Context.SpatialContext
fieldName	string
return	Lucene.Net.Documents

ToString() public method

public ToString ( ) : string
return	string

Property Details

ctx protected_oe property

protected SpatialContext,Spatial4n.Core.Context ctx
return	Spatial4n.Core.Context.SpatialContext