org.apache.lucene.spatial.vector

Class PointVectorStrategy

java.lang.Object

org.apache.lucene.spatial.SpatialStrategy

org.apache.lucene.spatial.vector.PointVectorStrategy

public class PointVectorStrategy
extends SpatialStrategy

Simple SpatialStrategy which represents Points in two numeric DoubleFields. The Strategy's best feature is decent distance sort.

Characteristics:

• Only indexes points; just one per field value.
• Can query by a rectangle or circle.
• SpatialOperation.Intersects and SpatialOperation.IsWithin is supported.
• Uses the FieldCache for SpatialStrategy.makeDistanceValueSource(com.spatial4j.core.shape.Point) and for searching with a Circle.

Implementation:

This is a simple Strategy. Search works with NumericRangeQuerys on an x and y pair of fields. A Circle query does the same bbox query but adds a ValueSource filter on SpatialStrategy.makeDistanceValueSource(com.spatial4j.core.shape.Point).

One performance shortcoming with this strategy is that a scenario involving both a search using a Circle and sort will result in calculations for the spatial distance being done twice -- once for the filter and second for the sort.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field and Description
int	precisionStep
static String	SUFFIX_X
static String	SUFFIX_Y

Fields inherited from class org.apache.lucene.spatial.SpatialStrategy

ctx

Constructor Summary

Constructors

Constructor and Description
PointVectorStrategy(com.spatial4j.core.context.SpatialContext ctx, String fieldNamePrefix)

Method Summary

Methods

Modifier and Type	Method and Description
Field[]	createIndexableFields(com.spatial4j.core.shape.Point point)
Field[]	createIndexableFields(com.spatial4j.core.shape.Shape shape) Returns the IndexableField(s) from the shape that are to be added to the Document.
ValueSource	makeDistanceValueSource(com.spatial4j.core.shape.Point queryPoint, double multiplier) Make a ValueSource returning the distance between the center of the indexed shape and queryPoint.
Filter	makeFilter(SpatialArgs args) Make a Filter based principally on SpatialOperation and Shape from the supplied args.
ConstantScoreQuery	makeQuery(SpatialArgs args) Make a Query based principally on SpatialOperation and Shape from the supplied args.
Query	makeQueryDistanceScore(SpatialArgs args)
void	setPrecisionStep(int p)

Methods inherited from class org.apache.lucene.spatial.SpatialStrategy

getFieldName, getSpatialContext, makeDistanceValueSource, makeRecipDistanceValueSource, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

SUFFIX_X

public static final String SUFFIX_X

See Also:

Constant Field Values

SUFFIX_Y

public static final String SUFFIX_Y

See Also:

Constant Field Values

precisionStep

public int precisionStep

Constructor Detail

PointVectorStrategy

public PointVectorStrategy(com.spatial4j.core.context.SpatialContext ctx,
                   String fieldNamePrefix)

Method Detail

setPrecisionStep

public void setPrecisionStep(int p)

createIndexableFields

public Field[] createIndexableFields(com.spatial4j.core.shape.Shape shape)

Description copied from class: SpatialStrategy

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.

Specified by:

createIndexableFields in class SpatialStrategy

Returns:

Not null nor will it have null elements.

createIndexableFields

public Field[] createIndexableFields(com.spatial4j.core.shape.Point point)

See Also:

createIndexableFields(com.spatial4j.core.shape.Shape)

makeDistanceValueSource

public ValueSource makeDistanceValueSource(com.spatial4j.core.shape.Point queryPoint,
                                  double multiplier)

Description copied from class: SpatialStrategy

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.

Specified by:

makeDistanceValueSource in class SpatialStrategy

makeFilter

public Filter makeFilter(SpatialArgs args)

Description copied from class: SpatialStrategy

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

If a subclasses implements SpatialStrategy.makeQuery(org.apache.lucene.spatial.query.SpatialArgs) then this method could be simply:

return new QueryWrapperFilter(makeQuery(args).getQuery());

Specified by:

makeFilter in class SpatialStrategy

makeQuery

public ConstantScoreQuery makeQuery(SpatialArgs args)

Description copied from class: SpatialStrategy

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

return new ConstantScoreQuery(makeFilter(args));

Overrides:

makeQuery in class SpatialStrategy

makeQueryDistanceScore

public Query makeQueryDistanceScore(SpatialArgs args)