org.apache.lucene.document

## Class LatLonPoint

- java.lang.Object
- - org.apache.lucene.document.Field
  - - org.apache.lucene.document.LatLonPoint

- All Implemented Interfaces:
    IndexableField

      public class LatLonPoint
      extends Field

  An indexed location field.

  Finding all documents within a range at search time is efficient. Multiple values for the same field in one document is allowed.

  This field defines static factory methods for common operations:

  - `newBoxQuery()` for matching points within a bounding box.
  - `newDistanceQuery()` for matching points within a specified distance.
  - `newPolygonQuery()` for matching points within an arbitrary polygon.
  - `nearest()` for finding the k-nearest neighbors by distance.

  If you also need per-document operations such as sort by distance, add a separate `LatLonDocValuesField` instance. If you also need to store the value, you should add a separate `StoredField` instance.

  WARNING: Values are indexed with some loss of precision from the original `double` values (4.190951585769653E-8 for the latitude component and 8.381903171539307E-8 for longitude).

  See Also:
    `PointValues`, `LatLonDocValuesField`

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class org.apache.lucene.document.Field

      `Field.Store`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static int` | `BYTES` LatLonPoint is encoded as integer values so number of bytes is 4
    `static FieldType` | `TYPE` Type for an indexed LatLonPoint

    - ### Fields inherited from class org.apache.lucene.document.Field

      `fieldsData, name, tokenStream, type`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `LatLonPoint(String name, double latitude, double longitude)` Creates a new LatLonPoint with the specified latitude and longitude

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and 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.
    `static Query` | `newBoxQuery(String field, double minLatitude, double maxLatitude, double minLongitude, double maxLongitude)` Create a query for matching a bounding box.
    `static Query` | `newDistanceQuery(String field, double latitude, double longitude, double radiusMeters)` Create a query for matching points within the specified distance of the supplied location.
    `static Query` | `newPolygonQuery(String field, Polygon... polygons)` Create a query for matching one or more polygons.
    `void` | `setLocationValue(double latitude, double longitude)` Change the values of this field
    `String` | `toString()`

    - ### Methods inherited from class org.apache.lucene.document.Field

      `binaryValue, fieldType, name, numericValue, readerValue, setBytesValue, setBytesValue, setByteValue, setDoubleValue, setFloatValue, setIntValue, setLongValue, setReaderValue, setShortValue, setStringValue, setTokenStream, stringValue, tokenStream, tokenStreamValue`

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### BYTES

          public static final int BYTES

      LatLonPoint is encoded as integer values so number of bytes is 4
      See Also:
        Constant Field Values

    - #### TYPE

          public static final FieldType TYPE

      Type for an indexed LatLonPoint

      Each point stores two dimensions with 4 bytes per dimension.

  - ### Constructor Detail

    - #### LatLonPoint

          public LatLonPoint(String name,
                             double latitude,
                             double longitude)

      Creates a new LatLonPoint with the specified latitude and longitude
      Parameters:
        `name` - field name
        `latitude` - latitude value: must be within standard +/-90 coordinate bounds.
        `longitude` - longitude value: must be within standard +/-180 coordinate bounds.
      Throws:
        `IllegalArgumentException` - if the field name is null or latitude or longitude are out of bounds

  - ### Method Detail

    - #### setLocationValue

          public void setLocationValue(double latitude,
                                       double longitude)

      Change the values of this field
      Parameters:
        `latitude` - latitude value: must be within standard +/-90 coordinate bounds.
        `longitude` - longitude value: must be within standard +/-180 coordinate bounds.
      Throws:
        `IllegalArgumentException` - if latitude or longitude are out of bounds

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Field`

    - #### newBoxQuery

          public static Query newBoxQuery(String field,
                                          double minLatitude,
                                          double maxLatitude,
                                          double minLongitude,
                                          double maxLongitude)

      Create a query for matching a bounding box.

      The box may cross over the dateline.

      Parameters:
        `field` - field name. must not be null.
        `minLatitude` - latitude lower bound: must be within standard +/-90 coordinate bounds.
        `maxLatitude` - latitude upper bound: must be within standard +/-90 coordinate bounds.
        `minLongitude` - longitude lower bound: must be within standard +/-180 coordinate bounds.
        `maxLongitude` - longitude upper bound: must be within standard +/-180 coordinate bounds.
      Returns:
        query matching points within this box
      Throws:
        `IllegalArgumentException` - if `field` is null, or the box has invalid coordinates.

    - #### newDistanceQuery

          public static Query newDistanceQuery(String field,
                                               double latitude,
                                               double longitude,
                                               double radiusMeters)

      Create a query for matching points within the specified distance of the supplied location.
      Parameters:
        `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.
        `radiusMeters` - maximum distance from the center in meters: must be non-negative and finite.
      Returns:
        query matching points within this distance
      Throws:
        `IllegalArgumentException` - if `field` is null, location has invalid coordinates, or radius is invalid.

    - #### newPolygonQuery

          public static Query newPolygonQuery(String field,
                                              Polygon... polygons)

      Create a query for matching one or more polygons.
      Parameters:
        `field` - field name. must not be null.
        `polygons` - array of polygons. must not be null or empty
      Returns:
        query matching points within this polygon
      Throws:
        `IllegalArgumentException` - if `field` is null, `polygons` is null or empty
      See Also:
        `Polygon`

    - #### 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 `Lucene60PointsFormat` (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.

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