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author
Silvio Heuberger
committed
- added bounding box expansion to the geohash
 bounding box search. - also added a method to get a bounding box as WKT.
1 parent d565bde commit 6d0d50e

5 files changed

Lines changed: 101 additions & 4 deletions

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‎src/main/java/ch/hsr/geohash/BoundingBox.java‎

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -94,4 +94,35 @@ public WGS84Point getCenterPoint() {
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double centerLongitude = (minLon + maxLon) / 2;
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return new WGS84Point(centerLatitude, centerLongitude);
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}
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public void expandToInclude(BoundingBox other) {
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if (other.minLon < minLon) {
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minLon = other.minLon;
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}
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if (other.maxLon > maxLon) {
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maxLon = other.maxLon;
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}
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if (other.minLat < minLat) {
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minLat = other.minLat;
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}
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if (other.maxLat > maxLat) {
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maxLat = other.maxLat;
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}
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}
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public double getMinLon() {
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return minLon;
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}
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public double getMinLat() {
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return minLat;
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}
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public double getMaxLat() {
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return maxLat;
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}
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public double getMaxLon() {
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return maxLon;
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}
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}

‎src/main/java/ch/hsr/geohash/queries/GeoHashBoundingBoxQuery.java‎

Lines changed: 21 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -25,26 +25,37 @@ public class GeoHashBoundingBoxQuery implements GeoHashQuery {
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/* there's not going to be more than 4 hashes. */
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private List<GeoHash> searchHashes = new ArrayList<GeoHash>(4);
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/* the combined bounding box of those hashes. */
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private BoundingBox boundingBox;
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public GeoHashBoundingBoxQuery(BoundingBox bbox) {
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int fittingBits = GeoHashSizeTable.numberOfBitsForOverlappingGeoHash(bbox);
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WGS84Point center = bbox.getCenterPoint();
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GeoHash centerHash = GeoHash.withBitPrecision(center.getLatitude(), center.getLongitude(), fittingBits);
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if (hashFits(centerHash, bbox)) {
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searchHashes.add(centerHash);
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addSearchHash(centerHash);
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} else {
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expandSearch(centerHash, bbox);
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}
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}
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private void addSearchHash(GeoHash hash) {
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if (boundingBox == null) {
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boundingBox = new BoundingBox(hash.getBoundingBox());
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} else {
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boundingBox.expandToInclude(hash.getBoundingBox());
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}
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searchHashes.add(hash);
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}
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private void expandSearch(GeoHash centerHash, BoundingBox bbox) {
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searchHashes.add(centerHash);
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addSearchHash(centerHash);
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for (GeoHash adjacent : centerHash.getAdjacent()) {
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BoundingBox adjacentBox = adjacent.getBoundingBox();
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if (adjacentBox.intersects(bbox) && !searchHashes.contains(adjacent)) {
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searchHashes.add(adjacent);
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addSearchHash(adjacent);
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}
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}
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}
@@ -73,4 +84,10 @@ public String toString() {
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}
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return bui.toString();
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}
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@Override
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public String getWktBox() {
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return "BOX(" + boundingBox.getMinLon() + " " + boundingBox.getMinLat() + "," + boundingBox.getMaxLon() + " "
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+ boundingBox.getMaxLat() + ")";
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}
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}

‎src/main/java/ch/hsr/geohash/queries/GeoHashCircleQuery.java‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -44,6 +44,11 @@ public GeoHashCircleQuery(WGS84Point center, double radius) {
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public boolean contains(GeoHash hash) {
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return query.contains(hash);
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}
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@Override
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public String getWktBox() {
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return query.getWktBox();
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}
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@Override
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public List<GeoHash> getSearchHashes() {

‎src/main/java/ch/hsr/geohash/queries/GeoHashQuery.java‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -16,4 +16,6 @@ public interface GeoHashQuery {
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*/
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public abstract List<GeoHash> getSearchHashes();
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public abstract String getWktBox();
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}

‎src/test/java/ch/hsr/geohash/GeoHashCircleQueryTest.java‎

Lines changed: 42 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,42 @@
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package ch.hsr.geohash;
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import static org.junit.Assert.*;
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import java.util.Arrays;
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import java.util.List;
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import org.junit.Test;
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import ch.hsr.geohash.queries.GeoHashCircleQuery;
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import ch.hsr.geohash.queries.GeoHashQuery;
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public class GeoHashCircleQueryTest {
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private WGS84Point center = new WGS84Point(10.00254, 76.30627);;
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@Test
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public void checkJerryDonSample1() {
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checkRadiusSearchHashes(1000, "t9y2bk" );
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}
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@Test
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public void testJerryDonSample2() {
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checkRadiusSearchHashes(1500, "t9y2bh", "t9y2bs", "t9yb2b0", "t9yb2b8");
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}
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@Test
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public void testJerryDonSample3() {
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checkRadiusSearchHashes(2500, "t9y2b");
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}
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private void checkRadiusSearchHashes(int radius, String ... string) {
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GeoHashQuery query = new GeoHashCircleQuery(center, radius);
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List<String> expectedHashes = Arrays.asList(string);
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List<GeoHash> searchHashes = query.getSearchHashes();
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assertEquals(expectedHashes.size(), searchHashes.size());
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for(GeoHash hash : searchHashes){
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if(! expectedHashes.contains(hash.toBase32())){
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fail("Hash " + hash + " not found in list of expected hashes");
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}
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}
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}
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}

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