com.spatial4j.core.io

Class GeohashUtils

java.lang.Object

com.spatial4j.core.io.GeohashUtils

public class GeohashUtils
extends Object

Utilities for encoding and decoding geohashes.

This class isn't used by any other part of Spatial4j; it's included largely for convenience of software using Spatial4j. There are other open-source libraries that have more comprehensive geohash utilities but providing this one avoids an additional dependency for what's a small amount of code. If you're using Spatial4j just for this class, consider alternatives.

This code originally came from Apache Lucene, LUCENE-1512.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_PRECISION

Method Summary

Methods

Modifier and Type	Method and Description
static Point	decode(String geohash, SpatialContext ctx) Decodes the given geohash into a latitude and longitude
static Rectangle	decodeBoundary(String geohash, SpatialContext ctx) Returns min-max lat, min-max lon.
static String	encodeLatLon(double latitude, double longitude) Encodes the given latitude and longitude into a geohash
static String	encodeLatLon(double latitude, double longitude, int precision)
static String[]	getSubGeohashes(String baseGeohash) Array of geohashes 1 level below the baseGeohash.
static double[]	lookupDegreesSizeForHashLen(int hashLen)
static int	lookupHashLenForWidthHeight(double lonErr, double latErr) Return the shortest geohash length that will have a width & height >= specified arguments.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_PRECISION

public static final int MAX_PRECISION

See Also:

Constant Field Values

Method Detail

encodeLatLon

public static String encodeLatLon(double latitude,
                  double longitude)

Encodes the given latitude and longitude into a geohash

Parameters:

latitude - Latitude to encode

longitude - Longitude to encode

Returns:

Geohash encoding of the longitude and latitude

encodeLatLon

public static String encodeLatLon(double latitude,
                  double longitude,
                  int precision)

decode

public static Point decode(String geohash,
           SpatialContext ctx)

Decodes the given geohash into a latitude and longitude

Parameters:

geohash - Geohash to deocde

Returns:

Array with the latitude at index 0, and longitude at index 1

decodeBoundary

public static Rectangle decodeBoundary(String geohash,
                       SpatialContext ctx)

Returns min-max lat, min-max lon.

getSubGeohashes

public static String[] getSubGeohashes(String baseGeohash)

Array of geohashes 1 level below the baseGeohash. Sorted.

lookupDegreesSizeForHashLen

public static double[] lookupDegreesSizeForHashLen(int hashLen)

lookupHashLenForWidthHeight

public static int lookupHashLenForWidthHeight(double lonErr,
                              double latErr)

Return the shortest geohash length that will have a width & height >= specified arguments.