Package org.apache.lucene.sandbox.search

Class LatLonPointPrototypeQueries

java.lang.Object

org.apache.lucene.sandbox.search.LatLonPointPrototypeQueries

public class LatLonPointPrototypeQueries
extends Object

Holder class for prototype sandboxed queries

When the query graduates from sandbox, these static calls should be placed in LatLonPoint

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

Method Summary

Modifier and Type	Method	Description
static TopFieldDocs	nearest(IndexSearcher searcher, String field, double latitude, double longitude, int n)	Finds the n nearest indexed points to the provided point, according to Haversine distance.

Methods inherited from class java.lang.Object

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

Method Details

nearest

public static TopFieldDocs nearest(IndexSearcher searcher,
 String field,
 double latitude,
 double longitude,
 int n)
                            throws IOException

Finds the n nearest indexed points to the provided point, according to Haversine distance.

This is functionally equivalent to running MatchAllDocsQuery with a LatLonDocValuesField.newDistanceSort(java.lang.String, double, double), but is far more efficient since it takes advantage of properties the indexed BKD tree. Currently this only works with Lucene90PointsFormat (used by the default codec). Multi-valued fields are currently not de-duplicated, so if a document had multiple instances of the specified field that make it into the top n, that document will appear more than once.

Documents are ordered by ascending distance from the location. The value returned in FieldDoc for the hits contains a Double instance with the distance in meters.

Parameters:

searcher - IndexSearcher to find nearest points from.

field - field name. must not be null.

latitude - latitude at the center: must be within standard +/-90 coordinate bounds.

longitude - longitude at the center: must be within standard +/-180 coordinate bounds.

n - the number of nearest neighbors to retrieve.

Returns:

TopFieldDocs containing documents ordered by distance, where the field value for each FieldDoc is the distance in meters

Throws:

IllegalArgumentException - if the underlying PointValues is not a Lucene60PointsReader (this is a current limitation), or if field or searcher is null, or if latitude, longitude or n are out-of-bounds

IOException - if an IOException occurs while finding the points.