sascha@3187: package de.intevation.flys.artifacts.model.sq;
sascha@3187: 
sascha@3187: import java.util.ArrayList;
sascha@3188: import java.util.Iterator;
sascha@3187: import java.util.List;
sascha@3187: 
sascha@3188: import org.apache.commons.math.MathException;
sascha@3188: 
sascha@3187: import org.apache.commons.math.stat.descriptive.moment.StandardDeviation;
sascha@3187: 
sascha@3187: public class Outlier
sascha@3187: {
sascha@3187:     public static final int MAX_ITERATIONS = 1000;
sascha@3187: 
sascha@3187:     public interface Callback {
sascha@3187: 
sascha@3187:         double eval(SQ sq);
sascha@3187: 
sascha@3187:         void iteration(int i);
sascha@3187: 
sascha@3187:         void outlier(SQ sq);
sascha@3187: 
sascha@3188:         void standardDeviation(double stdDev);
sascha@3188: 
sascha@3188:         void reinitialize(Iterator<SQ> good) throws MathException;
sascha@3188: 
sascha@3187:         void finished();
sascha@3187: 
sascha@3187:     } // interface Callback
sascha@3187: 
sascha@3187:     private static final class EvalSQ {
sascha@3187:         protected SQ     sq;
sascha@3187:         protected double value;
sascha@3187: 
sascha@3187:         public EvalSQ(SQ sq) {
sascha@3187:             this.sq = sq;
sascha@3187:         }
sascha@3187:     } // class EvalSQ
sascha@3187: 
sascha@3187:     public static List<SQ> detectOutliers(
sascha@3187:         Callback callback,
sascha@3187:         List<SQ> sqs,
sascha@3187:         double   stdDevFactor
sascha@3188:     )
sascha@3188:     throws MathException
sascha@3188:     {
sascha@3187:         List<EvalSQ> data = new ArrayList<EvalSQ>(sqs.size());
sascha@3187: 
sascha@3187:         for (SQ sq: sqs) {
sascha@3187:             data.add(new EvalSQ(sq));
sascha@3187:         }
sascha@3187: 
sascha@3187:         List<EvalSQ> good = new ArrayList<EvalSQ>(sqs.size());
sascha@3187: 
sascha@3188:         for (int i = 1; i <= MAX_ITERATIONS && data.size() > 2; ++i) {
sascha@3187: 
sascha@3187:             StandardDeviation stdDev = new StandardDeviation();
sascha@3187: 
sascha@3187:             for (EvalSQ esq: data) {
sascha@3187:                 stdDev.increment(esq.value = callback.eval(esq.sq));
sascha@3187:             }
sascha@3187: 
sascha@3188:             double sd = stdDev.getResult();
sascha@3188: 
sascha@3188:             callback.standardDeviation(sd);
sascha@3188: 
sascha@3188:             double accepted = stdDevFactor * sd;
sascha@3187: 
sascha@3187:             callback.iteration(i);
sascha@3187: 
sascha@3187:             for (EvalSQ esq: data) {
sascha@3187:                 if (Math.abs(esq.value) > accepted) {
sascha@3187:                     callback.outlier(esq.sq);
sascha@3187:                 }
sascha@3187:                 else {
sascha@3187:                     good.add(esq);
sascha@3187:                 }
sascha@3187:             }
sascha@3187: 
sascha@3187:             if (good.size() == data.size()) {
sascha@3187:                 break;
sascha@3187:             }
sascha@3187: 
sascha@3188:             callback.reinitialize(asSQIterator(good));
sascha@3188: 
sascha@3187:             List<EvalSQ> tmp = good;
sascha@3187:             good = data;
sascha@3187:             data = tmp;
sascha@3187:             good.clear();
sascha@3187:         }
sascha@3187: 
sascha@3187:         callback.finished();
sascha@3187: 
sascha@3187:         List<SQ> result = new ArrayList<SQ>(good.size());
sascha@3187: 
sascha@3187:         for (EvalSQ esq: good) {
sascha@3187:             result.add(esq.sq);
sascha@3187:         }
sascha@3187: 
sascha@3187:         return result;
sascha@3187:     }
sascha@3188: 
sascha@3188:     protected static Iterator<SQ> asSQIterator(List<EvalSQ> esqs) {
sascha@3188:         final Iterator<EvalSQ> parent = esqs.iterator();
sascha@3188:         return new Iterator<SQ>() {
sascha@3188:             @Override
sascha@3188:             public boolean hasNext() {
sascha@3188:                 return parent.hasNext();
sascha@3188:             }
sascha@3188: 
sascha@3188:             @Override
sascha@3188:             public SQ next() {
sascha@3188:                 return parent.next().sq;
sascha@3188:             }
sascha@3188: 
sascha@3188:             @Override
sascha@3188:             public void remove() {
sascha@3188:                 throw new UnsupportedOperationException();
sascha@3188:             }
sascha@3188:         };
sascha@3188:     }
sascha@3187: }
sascha@3187: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :