/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2005-2008, 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.feature.visitor;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.geotools.feature.FeatureCollection;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.filter.expression.Expression;
/**
* Obtains the data needed for a Quantile operation (classification of features into classes of equal size).
*
* The result contains an array of lists with the expression values in each.
*
* @author Cory Horner, Refractions Research Inc.
*
* @source $URL$
*/
public class QuantileListVisitor implements FeatureCalc {
private Expression expr;
private int count = 0;
private int bins;
private List items = new ArrayList();
private List[] bin;
boolean visited = false;
int countNull = 0;
int countNaN = 0;
public QuantileListVisitor(Expression expr, int bins) {
this.expr = expr;
this.bins = bins;
this.bin = new ArrayList[bins];
}
public void init(FeatureCollection<SimpleFeatureType, SimpleFeature> collection) {
//do nothing
}
public CalcResult getResult() {
if (bins == 0 || count == 0) return null;
// sort the list
Collections.sort(items);
if (bins > count) { //resize
bins = count;
this.bin = new ArrayList[bins];
}
// calculate number of items to put into each of the larger bins
int binPop = new Double(Math.ceil((double) count / bins)).intValue();
// determine index of bin where the next bin has one less item
int lastBigBin = count % bins;
if (lastBigBin == 0) lastBigBin = bins;
else lastBigBin--;
// put the items into their respective bins
int item = 0;
for (int binIndex = 0; binIndex < bins; binIndex++) {
bin[binIndex] = new ArrayList();
for (int binMember = 0; binMember < binPop; binMember++) {
bin[binIndex].add(items.get(item++));
}
if (lastBigBin == binIndex)
binPop--; // decrease the number of items in a bin for the next item
}
return new AbstractCalcResult() {
public Object getValue() {
return bin;
}
};
}
public void visit(SimpleFeature feature) {
visit((org.opengis.feature.Feature)feature);
}
public void visit(org.opengis.feature.Feature feature) {
Object value = expr.evaluate(feature);
if (value == null) {
countNull++; // increment the null count
return; // don't store this value
}
if (value instanceof Double) {
double doubleVal = ((Double) value).doubleValue();
if (Double.isNaN(doubleVal) || Double.isInfinite(doubleVal)) {
countNaN++; // increment the NaN count
return; // don't store NaN value
}
}
count++;
items.add(value);
}
public void reset(int bins) {
this.bins = bins;
this.count = 0;
this.items = new ArrayList();
this.bin = new ArrayList[bins];
this.countNull = 0;
this.countNaN = 0;
}
/**
* @return the number of features which returned a NaN
*/
public int getNaNCount() {
return countNaN;
}
/**
* @return the number of features which returned a null
*/
public int getNullCount() {
return countNull;
}
}