/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2014, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.process.spatialstatistics.pattern;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.data.simple.SimpleFeatureIterator;
import org.geotools.process.spatialstatistics.core.FeatureTypes;
import org.geotools.process.spatialstatistics.core.KnnSearch;
import org.geotools.process.spatialstatistics.core.SpatialEvent;
import org.geotools.process.spatialstatistics.operations.GeneralOperation;
import org.geotools.process.spatialstatistics.storage.IFeatureInserter;
import org.geotools.util.logging.Logging;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
import com.vividsolutions.jts.algorithm.ConvexHull;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.CoordinateArrays;
import com.vividsolutions.jts.geom.Envelope;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.index.strtree.ItemBoundable;
import com.vividsolutions.jts.index.strtree.ItemDistance;
import com.vividsolutions.jts.index.strtree.STRtree;
/**
* K-Nearest Neighbor Map - Spatial Clustering.
*
* @author Minpa Lee, MangoSystem
*
* @source $URL$
*/
public class KNearestNeighborMapOperation extends GeneralOperation {
protected static final Logger LOGGER = Logging.getLogger(KNearestNeighborMapOperation.class);
static String[] FIELDS = { "orig", "dest", "distance", "group" };
private int featureCount = 0;
public SimpleFeatureCollection execute(SimpleFeatureCollection features, int neighbor,
boolean convexHull) throws IOException {
// build spatial index
STRtree spatialIndex = buildSpatialIndex(features);
List<Coordinate> coordinates = new ArrayList<Coordinate>();
// create schema
String typeName = features.getSchema().getTypeName();
CoordinateReferenceSystem crs = features.getSchema().getCoordinateReferenceSystem();
SimpleFeatureType schema = FeatureTypes.getDefaultType(typeName, LineString.class, crs);
int length = typeName.length() + String.valueOf(featureCount).length() + 2;
schema = FeatureTypes.add(schema, FIELDS[0], String.class, length);
schema = FeatureTypes.add(schema, FIELDS[1], String.class, length);
schema = FeatureTypes.add(schema, FIELDS[2], Double.class, 38);
schema = FeatureTypes.add(schema, FIELDS[3], String.class, 20);
// build feature
IFeatureInserter featureWriter = getFeatureWriter(schema);
SimpleFeatureIterator featureIter = features.features();
try {
KnnSearch knnSearch = new KnnSearch(spatialIndex);
while (featureIter.hasNext()) {
SimpleFeature feature = featureIter.next();
Geometry geometry = (Geometry) feature.getDefaultGeometry();
Coordinate coordinate = geometry.getCentroid().getCoordinate();
if (convexHull) {
coordinates.add(coordinate);
}
SpatialEvent start = new SpatialEvent(feature.getID(), coordinate);
Object[] knns = knnSearch.kNearestNeighbour(new Envelope(coordinate), start,
new ItemDistance() {
@Override
public double distance(ItemBoundable item1, ItemBoundable item2) {
SpatialEvent s1 = (SpatialEvent) item1.getItem();
SpatialEvent s2 = (SpatialEvent) item2.getItem();
if (s1.id.equals(s2.id)) {
return Double.MAX_VALUE;
}
return s1.distance(s2);
}
}, neighbor);
// build line & write feature
for (Object object : knns) {
SpatialEvent nearest = (SpatialEvent) object;
Geometry line = createLineString(start, nearest);
double distance = line.getLength();
if (distance == 0) {
continue;
}
SimpleFeature newFeature = featureWriter.buildFeature();
newFeature.setDefaultGeometry(line);
newFeature.setAttribute(FIELDS[0], start.id);
newFeature.setAttribute(FIELDS[1], nearest.id);
newFeature.setAttribute(FIELDS[2], distance);
newFeature.setAttribute(FIELDS[3], "Nearest");
featureWriter.write(newFeature);
}
}
// finally convexhull
if (convexHull) {
Coordinate[] coords = CoordinateArrays.toCoordinateArray(coordinates);
ConvexHull cvxBuidler = new ConvexHull(coords, new GeometryFactory());
Geometry convexHullGeom = cvxBuidler.getConvexHull();
SimpleFeature newFeature = featureWriter.buildFeature();
newFeature.setDefaultGeometry(convexHullGeom.getBoundary());
newFeature.setAttribute(FIELDS[3], "ConvexHull");
featureWriter.write(newFeature);
}
} catch (Exception e) {
featureWriter.rollback(e);
} finally {
featureWriter.close(featureIter);
}
return featureWriter.getFeatureCollection();
}
private Geometry createLineString(SpatialEvent start, SpatialEvent end) {
return gf.createLineString(new Coordinate[] { start.getCoordinate(), end.getCoordinate() });
}
private STRtree buildSpatialIndex(SimpleFeatureCollection features) {
STRtree spatialIndex = new STRtree();
SimpleFeatureIterator featureIter = features.features();
try {
while (featureIter.hasNext()) {
SimpleFeature feature = featureIter.next();
Geometry geometry = (Geometry) feature.getDefaultGeometry();
Coordinate centroid = geometry.getCentroid().getCoordinate();
SpatialEvent event = new SpatialEvent(feature.getID(), centroid);
spatialIndex.insert(new Envelope(centroid), event);
featureCount++;
}
} finally {
featureIter.close();
}
return spatialIndex;
}
}