package de.lmu.ifi.dbs.elki.algorithm.outlier.spatial;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2011
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import de.lmu.ifi.dbs.elki.algorithm.outlier.spatial.neighborhood.NeighborSetPredicate;
import de.lmu.ifi.dbs.elki.data.NumberVector;
import de.lmu.ifi.dbs.elki.data.type.TypeInformation;
import de.lmu.ifi.dbs.elki.data.type.TypeUtil;
import de.lmu.ifi.dbs.elki.database.datastore.DataStoreFactory;
import de.lmu.ifi.dbs.elki.database.datastore.DataStoreUtil;
import de.lmu.ifi.dbs.elki.database.datastore.WritableDataStore;
import de.lmu.ifi.dbs.elki.database.ids.DBID;
import de.lmu.ifi.dbs.elki.database.ids.DBIDs;
import de.lmu.ifi.dbs.elki.database.relation.MaterializedRelation;
import de.lmu.ifi.dbs.elki.database.relation.Relation;
import de.lmu.ifi.dbs.elki.logging.Logging;
import de.lmu.ifi.dbs.elki.math.DoubleMinMax;
import de.lmu.ifi.dbs.elki.math.linearalgebra.CovarianceMatrix;
import de.lmu.ifi.dbs.elki.math.linearalgebra.Matrix;
import de.lmu.ifi.dbs.elki.math.linearalgebra.Vector;
import de.lmu.ifi.dbs.elki.math.statistics.QuickSelect;
import de.lmu.ifi.dbs.elki.result.outlier.BasicOutlierScoreMeta;
import de.lmu.ifi.dbs.elki.result.outlier.OutlierResult;
import de.lmu.ifi.dbs.elki.result.outlier.OutlierScoreMeta;
import de.lmu.ifi.dbs.elki.utilities.DatabaseUtil;
import de.lmu.ifi.dbs.elki.utilities.documentation.Reference;
/**
* Median Approach is used to discover spatial outliers with multiple
* attributes.
*
* <p>
* Reference:<br>
* Chang-Tien Lu and Dechang Chen and Yufeng Kou:<br>
* Detecting Spatial Outliers with Multiple Attributes<br>
* in 15th IEEE International Conference on Tools with Artificial Intelligence,
* 2003
* </p>
*
* <p>
* Implementation note: attribute standardization is not used; this is
* equivalent to using the
* {@link de.lmu.ifi.dbs.elki.datasource.filter.AttributeWiseVarianceNormalization
* AttributeWiseVarianceNormalization} filter.
* </p>
*
* @author Ahmed Hettab
*
* @param <N> Spatial Vector
* @param <O> Non Spatial Vector
*/
@Reference(authors = "Chang-Tien Lu and Dechang Chen and Yufeng Kou", title = "Detecting Spatial Outliers with Multiple Attributes", booktitle = "Proc. 15th IEEE International Conference on Tools with Artificial Intelligence, 2003", url = "http://dx.doi.org/10.1109/TAI.2003.1250179")
public class CTLuMedianMultipleAttributes<N, O extends NumberVector<?, ?>> extends AbstractNeighborhoodOutlier<N> {
/**
* logger
*/
public static final Logging logger = Logging.getLogger(CTLuMedianMultipleAttributes.class);
/**
* Constructor
*
* @param npredf Neighborhood predicate
*/
public CTLuMedianMultipleAttributes(NeighborSetPredicate.Factory<N> npredf) {
super(npredf);
}
@Override
protected Logging getLogger() {
return logger;
}
/**
* Run the algorithm
*
* @param spatial Spatial relation
* @param attributes Attributes relation
* @return Outlier detection result
*/
public OutlierResult run(Relation<N> spatial, Relation<O> attributes) {
final int dim = DatabaseUtil.dimensionality(attributes);
if(logger.isDebugging()) {
logger.debug("Dimensionality: " + dim);
}
final NeighborSetPredicate npred = getNeighborSetPredicateFactory().instantiate(spatial);
CovarianceMatrix covmaker = new CovarianceMatrix(dim);
WritableDataStore<Vector> deltas = DataStoreUtil.makeStorage(attributes.getDBIDs(), DataStoreFactory.HINT_TEMP, Vector.class);
for(DBID id : attributes.iterDBIDs()) {
final O obj = attributes.get(id);
final DBIDs neighbors = npred.getNeighborDBIDs(id);
// Compute the median vector
final Vector median;
{
double[][] data = new double[dim][neighbors.size()];
int i = 0;
// Load data
for(DBID n : neighbors) {
// TODO: skip object itself within neighbors?
O nobj = attributes.get(n);
for(int d = 0; d < dim; d++) {
data[d][i] = nobj.doubleValue(d + 1);
}
i++;
}
double[] md = new double[dim];
for(int d = 0; d < dim; d++) {
md[d] = QuickSelect.median(data[d]);
}
median = new Vector(md);
}
// Delta vector "h"
Vector delta = obj.getColumnVector().minus(median);
deltas.put(id, delta);
covmaker.put(delta);
}
// Finalize covariance matrix:
Vector mean = covmaker.getMeanVector();
Matrix cmati = covmaker.destroyToSampleMatrix().inverse();
DoubleMinMax minmax = new DoubleMinMax();
WritableDataStore<Double> scores = DataStoreUtil.makeStorage(attributes.getDBIDs(), DataStoreFactory.HINT_STATIC, Double.class);
for(DBID id : attributes.iterDBIDs()) {
Vector temp = deltas.get(id).minus(mean);
final Vector res = temp.transposeTimes(cmati).times(temp);
assert (res.getDimensionality() == 1);
double score = res.get(0);
minmax.put(score);
scores.put(id, score);
}
Relation<Double> scoreResult = new MaterializedRelation<Double>("Median multiple attributes outlier", "median-outlier", TypeUtil.DOUBLE, scores, attributes.getDBIDs());
OutlierScoreMeta scoreMeta = new BasicOutlierScoreMeta(minmax.getMin(), minmax.getMax(), 0.0, Double.POSITIVE_INFINITY, 0);
OutlierResult or = new OutlierResult(scoreMeta, scoreResult);
or.addChildResult(npred);
return or;
}
@Override
public TypeInformation[] getInputTypeRestriction() {
return TypeUtil.array(getNeighborSetPredicateFactory().getInputTypeRestriction(), TypeUtil.NUMBER_VECTOR_FIELD);
}
/**
* Parameterization class.
*
* @author Ahmed Hettab
*
* @apiviz.exclude
*
* @param <N> Neighborhood type
* @param <O> Attributes vector type
*/
public static class Parameterizer<N, O extends NumberVector<?, ?>> extends AbstractNeighborhoodOutlier.Parameterizer<N> {
@Override
protected CTLuMedianMultipleAttributes<N, O> makeInstance() {
return new CTLuMedianMultipleAttributes<N, O>(npredf);
}
}
}