LUCENE-2147: Improve Spatial Utility like classes

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@896240 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Simon Willnauer 2010-01-05 22:03:48 +00:00
parent 36ba04585e
commit c19d78dd4e
5 changed files with 338 additions and 152 deletions

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@ -33,6 +33,10 @@ API Changes
* LUCENE-2108: Add SpellChecker.close, to close the underlying
reader. (Eirik Bjørsnøs via Mike McCandless)
* LUCENE-2147: Spatial GeoHashUtils now always decode GeoHash strings
with full precision. GeoHash#decode_exactly(String) was merged into
GeoHash#decode(String). (Chris Male, Simon Willnauer)
* LUCENE-2165: Add a constructor to SnowballAnalyzer that takes a Set of
stopwords, and deprecate the String[] one. (Nick Burch via Robert Muir)

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@ -21,84 +21,73 @@ import java.util.HashMap;
import java.util.Map;
/**
* Based on http://en.wikipedia.org/wiki/Geohash
*
* <p><font color="red"><b>NOTE:</b> This API is still in
* flux and might change in incompatible ways in the next
* release.</font>
* Utilities for encoding and decoding geohashes. Based on
* http://en.wikipedia.org/wiki/Geohash.
*/
public class GeoHashUtils {
// geohash's char map
// no a's i's l's o's
// old MacDonal wouldn't be happy
private static char[] _base32 = {'0','1','2','3','4','5','6','7','8','9',
'b','c','d','e','f','g','h','j','k','m',
'n','p','q','r','s','t','u','v','w','x',
'y','z'} ;
private static final char[] BASE_32 = {'0', '1', '2', '3', '4', '5', '6',
'7', '8', '9', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'm', 'n',
'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
private final static Map<Character,Integer> DECODE_MAP = new HashMap<Character,Integer>();
private static final int PRECISION = 12;
private static final int[] BITS = {16, 8, 4, 2, 1};
private final static Map<Character, Integer> _decodemap = new HashMap<Character, Integer>();
static {
int sz = _base32.length;
for (int i = 0; i < sz; i++ ){
_decodemap.put(_base32[i], i);
for (int i = 0; i < BASE_32.length; i++) {
DECODE_MAP.put(Character.valueOf(BASE_32[i]), Integer.valueOf(i));
}
}
private static int precision = 12;
private static int[] bits = {16, 8, 4, 2, 1};
public static void main(String[] args) {
GeoHashUtils ghf = new GeoHashUtils();
String gc1 = ghf.encode(30, -90.0);
String gc2 = ghf.encode(51.4797, -0.0124);
System.out.println(gc1);
System.out.println(gc2);
double [] gd1 = ghf.decode(gc1);
double [] gd2 = ghf.decode(gc2);
System.out.println(gd1[0]+ ", "+ gd1[1]);
System.out.println(gd2[0]+ ", "+ gd2[1]);
private GeoHashUtils() {
}
public static String encode(double latitude, double longitude){
double[] lat_interval = {-90.0 , 90.0};
double[] lon_interval = {-180.0, 180.0};
/**
* Encodes the given latitude and longitude into a geohash
*
* @param latitude Latitude to encode
* @param longitude Longitude to encode
* @return Geohash encoding of the longitude and latitude
*/
public static String encode(double latitude, double longitude) {
double[] latInterval = {-90.0, 90.0};
double[] lngInterval = {-180.0, 180.0};
StringBuilder geohash = new StringBuilder();
boolean is_even = true;
int bit = 0, ch = 0;
final StringBuilder geohash = new StringBuilder();
boolean isEven = true;
while(geohash.length() < precision){
int bit = 0;
int ch = 0;
while (geohash.length() < PRECISION) {
double mid = 0.0;
if(is_even){
mid = (lon_interval[0] + lon_interval[1]) / 2;
if (longitude > mid){
ch |= bits[bit];
lon_interval[0] = mid;
if (isEven) {
mid = (lngInterval[0] + lngInterval[1]) / 2D;
if (longitude > mid) {
ch |= BITS[bit];
lngInterval[0] = mid;
} else {
lon_interval[1] = mid;
lngInterval[1] = mid;
}
} else {
mid = (lat_interval[0] + lat_interval[1]) / 2;
if(latitude > mid){
ch |= bits[bit];
lat_interval[0] = mid;
mid = (latInterval[0] + latInterval[1]) / 2D;
if (latitude > mid) {
ch |= BITS[bit];
latInterval[0] = mid;
} else {
lat_interval[1] = mid;
latInterval[1] = mid;
}
}
is_even = is_even ? false : true;
isEven = !isEven;
if (bit < 4){
bit ++;
if (bit < 4) {
bit++;
} else {
geohash.append(_base32[ch]);
bit =0;
geohash.append(BASE_32[ch]);
bit = 0;
ch = 0;
}
}
@ -106,69 +95,45 @@ public class GeoHashUtils {
return geohash.toString();
}
/**
* Decodes the given geohash into a latitude and longitude
*
* @param geohash Geohash to deocde
* @return Array with the latitude at index 0, and longitude at index 1
*/
public static double[] decode(String geohash) {
double[] ge = decode_exactly(geohash);
double lat, lon, lat_err, lon_err;
lat = ge[0];
lon = ge[1];
lat_err = ge[2];
lon_err = ge[3];
final double[] latInterval = {-90.0, 90.0};
final double[] lngInterval = {-180.0, 180.0};
double lat_precision = Math.max(1, Math.round(- Math.log10(lat_err))) - 1;
double lon_precision = Math.max(1, Math.round(- Math.log10(lon_err))) - 1;
boolean isEven = true;
lat = getPrecision(lat, lat_precision);
lon = getPrecision(lon, lon_precision);
double latitude;
double longitude;
for (int i = 0; i < geohash.length(); i++) {
final int cd = DECODE_MAP.get(Character.valueOf(
geohash.charAt(i))).intValue();
return new double[] {lat, lon};
}
public static double[] decode_exactly (String geohash){
double[] lat_interval = {-90.0 , 90.0};
double[] lon_interval = {-180.0, 180.0};
double lat_err = 90.0;
double lon_err = 180.0;
boolean is_even = true;
int sz = geohash.length();
int bsz = bits.length;
double latitude, longitude;
for (int i = 0; i < sz; i++){
int cd = _decodemap.get(geohash.charAt(i));
for (int z = 0; z< bsz; z++){
int mask = bits[z];
if (is_even){
lon_err /= 2;
if ((cd & mask) != 0){
lon_interval[0] = (lon_interval[0]+lon_interval[1])/2;
for (int mask : BITS) {
if (isEven) {
if ((cd & mask) != 0) {
lngInterval[0] = (lngInterval[0] + lngInterval[1]) / 2D;
} else {
lon_interval[1] = (lon_interval[0]+lon_interval[1])/2;
lngInterval[1] = (lngInterval[0] + lngInterval[1]) / 2D;
}
} else {
lat_err /=2;
if ( (cd & mask) != 0){
lat_interval[0] = (lat_interval[0]+lat_interval[1])/2;
if ((cd & mask) != 0) {
latInterval[0] = (latInterval[0] + latInterval[1]) / 2D;
} else {
lat_interval[1] = (lat_interval[0]+lat_interval[1])/2;
latInterval[1] = (latInterval[0] + latInterval[1]) / 2D;
}
}
is_even = is_even ? false : true;
isEven = !isEven;
}
}
latitude = (lat_interval[0] + lat_interval[1]) / 2;
longitude = (lon_interval[0] + lon_interval[1]) / 2;
latitude = (latInterval[0] + latInterval[1]) / 2D;
longitude = (lngInterval[0] + lngInterval[1]) / 2D;
return new double []{latitude, longitude, lat_err, lon_err};
}
static double getPrecision(double x, double precision) {
double base = Math.pow(10,- precision);
double diff = x % base;
return x - diff;
return new double[] {latitude, longitude};
}
}

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@ -18,11 +18,93 @@
package org.apache.lucene.spatial.geometry;
/**
* <p><font color="red"><b>NOTE:</b> This API is still in
* flux and might change in incompatible ways in the next
* release.</font>
* Enum representing difference distance units, currently only kilometers and
* miles
*/
public enum DistanceUnits {
MILES,
KILOMETERS;
MILES("miles", 3959, 24902),
KILOMETERS("km", 6371, 40076);
private static final double MILES_KILOMETRES_RATIO = 1.609344;
private final String unit;
private final double earthCircumference;
private final double earthRadius;
/**
* Creates a new DistanceUnit that represents the given unit
*
* @param unit Distance unit in String form
* @param earthRadius Radius of the Earth in the specific distance unit
* @param earthCircumfence Circumference of the Earth in the specific distance unit
*/
DistanceUnits(String unit, double earthRadius, double earthCircumfence) {
this.unit = unit;
this.earthCircumference = earthCircumfence;
this.earthRadius = earthRadius;
}
/**
* Returns the DistanceUnit which represents the given unit
*
* @param unit Unit whose DistanceUnit should be found
* @return DistanceUnit representing the unit
* @throws IllegalArgumentException if no DistanceUnit which represents the given unit is found
*/
public static DistanceUnits findDistanceUnit(String unit) {
if (MILES.getUnit().equals(unit)) {
return MILES;
}
if (KILOMETERS.getUnit().equals(unit)) {
return KILOMETERS;
}
throw new IllegalArgumentException("Unknown distance unit " + unit);
}
/**
* Converts the given distance in given DistanceUnit, to a distance in the unit represented by {@code this}
*
* @param distance Distance to convert
* @param from Unit to convert the distance from
* @return Given distance converted to the distance in the given unit
*/
public double convert(double distance, DistanceUnits from) {
if (from == this) {
return distance;
}
return (this == MILES) ? distance / MILES_KILOMETRES_RATIO : distance * MILES_KILOMETRES_RATIO;
}
/**
* Returns the string representation of the distance unit
*
* @return String representation of the distance unit
*/
public String getUnit() {
return unit;
}
/**
* Returns the <a href="http://en.wikipedia.org/wiki/Earth_radius">average earth radius</a>
*
* @return the average earth radius
*/
public double earthRadius() {
return earthRadius;
}
/**
* Returns the <a href="http://www.lyberty.com/encyc/articles/earth.html">circumference of the Earth</a>
*
* @return the circumference of the Earth
*/
public double earthCircumference() {
return earthCircumference;
}
}

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@ -0,0 +1,89 @@
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.spatial.geohash;
import static junit.framework.Assert.*;
import org.junit.Test;
/**
* Tests for {@link GeoHashUtils}
*/
public class TestGeoHashUtils {
/**
* Pass condition: lat=42.6, lng=-5.6 should be encoded as "ezs42e44yx96",
* lat=57.64911 lng=10.40744 should be encoded as "u4pruydqqvj8"
*/
@Test
public void testEncode() {
String hash = GeoHashUtils.encode(42.6, -5.6);
assertEquals("ezs42e44yx96", hash);
hash = GeoHashUtils.encode(57.64911, 10.40744);
assertEquals("u4pruydqqvj8", hash);
}
/**
* Pass condition: lat=52.3738007, lng=4.8909347 should be encoded and then
* decoded within 0.00001 of the original value
*/
@Test
public void testDecodePreciseLongitudeLatitude() {
String hash = GeoHashUtils.encode(52.3738007, 4.8909347);
double[] latitudeLongitude = GeoHashUtils.decode(hash);
assertEquals(52.3738007, latitudeLongitude[0], 0.00001D);
assertEquals(4.8909347, latitudeLongitude[1], 0.00001D);
}
/**
* Pass condition: lat=84.6, lng=10.5 should be encoded and then decoded
* within 0.00001 of the original value
*/
@Test
public void testDecodeImpreciseLongitudeLatitude() {
String hash = GeoHashUtils.encode(84.6, 10.5);
double[] latitudeLongitude = GeoHashUtils.decode(hash);
assertEquals(84.6, latitudeLongitude[0], 0.00001D);
assertEquals(10.5, latitudeLongitude[1], 0.00001D);
}
/*
* see https://issues.apache.org/jira/browse/LUCENE-1815 for details
*/
@Test
public void testDecodeEncode() {
String geoHash = "u173zq37x014";
assertEquals(geoHash, GeoHashUtils.encode(52.3738007, 4.8909347));
double[] decode = GeoHashUtils.decode(geoHash);
assertEquals(52.37380061d, decode[0], 0.000001d);
assertEquals(4.8909343d, decode[1], 0.000001d);
assertEquals(geoHash, GeoHashUtils.encode(decode[0], decode[1]));
geoHash = "u173";
decode = GeoHashUtils.decode("u173");
geoHash = GeoHashUtils.encode(decode[0], decode[1]);
assertEquals(decode[0], GeoHashUtils.decode(geoHash)[0], 0.000001d);
assertEquals(decode[1], GeoHashUtils.decode(geoHash)[1], 0.000001d);
}
}

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@ -0,0 +1,46 @@
package org.apache.lucene.spatial.geometry;
import static junit.framework.Assert.*;
import org.junit.Test;
/**
* Tests for {@link org.apache.lucene.spatial.geometry.DistanceUnits}
*/
public class TestDistanceUnits {
/**
* Pass condition: When finding the DistanceUnit for "km", KILOMETRES is found. When finding the DistanceUnit for
* "miles", MILES is found.
*/
@Test
public void testFindDistanceUnit() {
assertEquals(DistanceUnits.KILOMETERS, DistanceUnits.findDistanceUnit("km"));
assertEquals(DistanceUnits.MILES, DistanceUnits.findDistanceUnit("miles"));
}
/**
* Pass condition: Searching for the DistanceUnit of an unknown unit "mls" should throw an IllegalArgumentException.
*/
@Test
public void testFindDistanceUnit_unknownUnit() {
try {
DistanceUnits.findDistanceUnit("mls");
assertTrue("IllegalArgumentException should have been thrown", false);
} catch (IllegalArgumentException iae) {
// Expected
}
}
/**
* Pass condition: Converting between the same units should not change the value. Converting from MILES to KILOMETRES
* involves multiplying the distance by the ratio, and converting from KILOMETRES to MILES involves dividing by the ratio
*/
@Test
public void testConvert() {
assertEquals(10.5, DistanceUnits.MILES.convert(10.5, DistanceUnits.MILES), 0D);
assertEquals(10.5, DistanceUnits.KILOMETERS.convert(10.5, DistanceUnits.KILOMETERS), 0D);
assertEquals(10.5 * 1.609344, DistanceUnits.KILOMETERS.convert(10.5, DistanceUnits.MILES), 0D);
assertEquals(10.5 / 1.609344, DistanceUnits.MILES.convert(10.5, DistanceUnits.KILOMETERS), 0D);
}
}