/*
* 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.feature.gs;
import java.util.ArrayList;
import java.util.List;
import org.geotools.data.collection.ListFeatureCollection;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.feature.simple.SimpleFeatureBuilder;
import org.geotools.feature.simple.SimpleFeatureTypeBuilder;
import org.geotools.feature.visitor.UniqueVisitor;
import org.geotools.process.factory.DescribeParameter;
import org.geotools.process.factory.DescribeProcess;
import org.geotools.process.factory.DescribeResult;
import org.geotools.process.gs.GSProcess;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.feature.type.AttributeDescriptor;
import org.opengis.util.ProgressListener;
/**
* Returns the unique values of a certain attribute
*
* @author Andrea Aime
*
* @source $URL$
*/
@DescribeProcess(title = "Unique values", description = "Returns the unique values of a certain attribute")
public class UniqueProcess implements GSProcess {
// the functions this process can handle
public enum AggregationFunction {
Average, Max, Median, Min, StdDev, Sum;
}
@DescribeResult(name = "result", description = "The list of unique values extracted from the feature list")
public SimpleFeatureCollection execute(
@DescribeParameter(name = "features", description = "The feature collection that will be inspected") SimpleFeatureCollection features,
@DescribeParameter(name = "attribute", description = "The attribute whose unique values will be returned") String attribute,
ProgressListener progressListener) throws Exception {
int attIndex = -1;
List<AttributeDescriptor> atts = features.getSchema().getAttributeDescriptors();
for (int i = 0; i < atts.size(); i++) {
if (atts.get(i).getLocalName().equals(attribute)) {
attIndex = i;
break;
}
}
UniqueVisitor visitor = new UniqueVisitor(attIndex, features.getSchema());
features.accepts(visitor, progressListener);
List uniqueValues = visitor.getResult().toList();
SimpleFeatureTypeBuilder tb = new SimpleFeatureTypeBuilder();
tb.add("value", features.getSchema().getDescriptor(attIndex).getType().getBinding());
tb.setName("UniqueValue");
SimpleFeatureType ft = tb.buildFeatureType();
SimpleFeatureBuilder fb = new SimpleFeatureBuilder(ft);
ListFeatureCollection result = new ListFeatureCollection(ft);
for (Object value : uniqueValues) {
fb.add(value);
result.add(fb.buildFeature(null));
}
return result;
}
private List<String> attNames(List<AttributeDescriptor> atts) {
List<String> result = new ArrayList<String>();
for (AttributeDescriptor ad : atts) {
result.add(ad.getLocalName());
}
return result;
}
}