/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2011, Open Source Geospatial Foundation (OSGeo)
* (C) 2001-2007 TOPP - www.openplans.org.
*
* 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.vector;
import java.util.HashSet;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
import org.geotools.process.ProcessException;
import org.geotools.process.factory.DescribeParameter;
import org.geotools.process.factory.DescribeProcess;
import org.geotools.process.factory.DescribeResult;
import org.geotools.process.gs.WrappingIterator;
import org.geotools.process.vector.AggregateProcess.AggregationFunction;
import org.geotools.process.vector.AggregateProcess.Results;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.data.simple.SimpleFeatureIterator;
import org.geotools.factory.CommonFactoryFinder;
import org.geotools.feature.collection.DecoratingSimpleFeatureCollection;
import org.geotools.feature.simple.SimpleFeatureBuilder;
import org.geotools.feature.simple.SimpleFeatureTypeBuilder;
import org.geotools.geometry.jts.JTS;
import org.geotools.referencing.CRS;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.feature.type.AttributeDescriptor;
import org.opengis.feature.type.GeometryDescriptor;
import org.opengis.filter.Filter;
import org.opengis.filter.FilterFactory2;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
import com.vividsolutions.jts.geom.Geometry;
/**
* Provides statistics for the distribution of a certain quantity in a set of reference areas.
* The data layer must be a point layer, the reference layer must be a polygonal one
*/
@DescribeProcess(title = "Vector Zonal Statistics", description = "Computes statistics for the distribution of a given attribute in a set of polygonal zones. Input must be points.")
public class VectorZonalStatistics implements VectorProcess {
@DescribeResult(name = "statistics", description = "A feature collection with the attributes of the zone layer (prefixed by 'z_') and the statistics fields count,min,max,sum,avg,stddev")
public SimpleFeatureCollection execute(
@DescribeParameter(name = "data", description = "Input collection of point features") SimpleFeatureCollection data,
@DescribeParameter(name = "dataAttribute", description = "Attribute to use for computing statistics") String dataAttribute,
@DescribeParameter(name = "zones", description = "Zone polygon features for which to compute statistics") SimpleFeatureCollection zones) {
AttributeDescriptor dataDescriptor = data.getSchema().getDescriptor(dataAttribute);
if (dataDescriptor == null) {
throw new IllegalArgumentException("Attribute " + dataAttribute + " not found in "
+ data.getSchema());
}
return new ZonalStatisticsCollection(data, dataAttribute, zones);
}
/**
* A feature collection that computes zonal statitics in a streaming fashion
* @author Andrea Aime - OpenGeo
*/
static class ZonalStatisticsCollection extends DecoratingSimpleFeatureCollection {
SimpleFeatureCollection data;
String dataAttribute;
SimpleFeatureType targetSchema;
public ZonalStatisticsCollection(SimpleFeatureCollection data, String dataAttribute,
SimpleFeatureCollection zones) {
super(zones);
this.dataAttribute = dataAttribute;
this.data = data;
SimpleFeatureTypeBuilder tb = new SimpleFeatureTypeBuilder();
for (AttributeDescriptor att : zones.getSchema().getAttributeDescriptors()) {
tb.minOccurs(att.getMinOccurs());
tb.maxOccurs(att.getMaxOccurs());
tb.restrictions(att.getType().getRestrictions());
if (att instanceof GeometryDescriptor) {
GeometryDescriptor gatt = (GeometryDescriptor) att;
tb.crs(gatt.getCoordinateReferenceSystem());
}
tb.add("z_" + att.getLocalName(), att.getType().getBinding());
}
AttributeDescriptor dataDescriptor = data.getSchema().getDescriptor(dataAttribute);
tb.add("count", Long.class);
tb.add("min", Double.class);
tb.add("max", Double.class);
tb.add("sum", Double.class);
tb.add("avg", Double.class);
tb.add("stddev", Double.class);
tb.setName(zones.getSchema().getName());
targetSchema = tb.buildFeatureType();
}
@Override
public SimpleFeatureType getSchema() {
return targetSchema;
}
@Override
public SimpleFeatureIterator features() {
return new ZonalStatisticsIterator(delegate.features(), dataAttribute, data,
targetSchema);
}
}
/**
* An iterator computing statistics as we go
*/
static class ZonalStatisticsIterator implements SimpleFeatureIterator {
Set<AggregationFunction> FUNCTIONS = new HashSet<AggregationFunction>() {
{
add(AggregationFunction.Count);
add(AggregationFunction.Max);
add(AggregationFunction.Min);
add(AggregationFunction.Sum);
add(AggregationFunction.Average);
add(AggregationFunction.StdDev);
}
};
FilterFactory2 ff = CommonFactoryFinder.getFilterFactory2(null);
SimpleFeatureIterator zones;
String dataAttribute;
SimpleFeatureCollection data;
SimpleFeatureBuilder builder;
String dataGeomName;
public ZonalStatisticsIterator(SimpleFeatureIterator zones, String dataAttribute,
SimpleFeatureCollection data, SimpleFeatureType targetSchema) {
this.zones = zones;
this.dataAttribute = dataAttribute;
this.data = data;
this.builder = new SimpleFeatureBuilder(targetSchema);
this.dataGeomName = data.getSchema().getGeometryDescriptor().getLocalName();
}
public void close() {
zones.close();
}
public boolean hasNext() {
return zones.hasNext();
}
public SimpleFeature next() throws NoSuchElementException {
// grab the current zone
SimpleFeature zone = zones.next();
try {
// grab the geometry and eventually reproject it
Geometry zoneGeom = (Geometry) zone.getDefaultGeometry();
CoordinateReferenceSystem dataCrs = data.getSchema().getCoordinateReferenceSystem();
CoordinateReferenceSystem zonesCrs = builder.getFeatureType()
.getGeometryDescriptor().getCoordinateReferenceSystem();
if (!CRS.equalsIgnoreMetadata(zonesCrs, dataCrs)) {
zoneGeom = JTS.transform(zoneGeom, CRS.findMathTransform(zonesCrs, dataCrs,
true));
}
// build the filter and gather the statistics
Filter areaFilter = ff.within(ff.property(dataGeomName), ff.literal(zoneGeom));
SimpleFeatureCollection zoneCollection = data.subCollection(areaFilter);
Results stats = new AggregateProcess().execute(zoneCollection, dataAttribute,
FUNCTIONS, true, null);
// build the resulting feature
builder.addAll(zone.getAttributes());
if(stats != null) {
builder.add(stats.getCount());
builder.add(stats.getMin());
builder.add(stats.getMax());
builder.add(stats.getSum());
builder.add(stats.getAverage());
builder.add(stats.getStandardDeviation());
}
return builder.buildFeature(zone.getID());
} catch (Exception e) {
throw new ProcessException("Failed to compute statistics on feature " + zone, e);
}
}
}
}