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+package de.lmu.ifi.dbs.elki.algorithm.outlier.clustering;
+
+/*
+ This file is part of ELKI:
+ Environment for Developing KDD-Applications Supported by Index-Structures
+
+ Copyright (C) 2014
+ 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.AbstractAlgorithm;
+import de.lmu.ifi.dbs.elki.algorithm.clustering.em.EM;
+import de.lmu.ifi.dbs.elki.algorithm.outlier.OutlierAlgorithm;
+import de.lmu.ifi.dbs.elki.data.Clustering;
+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.Database;
+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.WritableDoubleDataStore;
+import de.lmu.ifi.dbs.elki.database.ids.DBIDIter;
+import de.lmu.ifi.dbs.elki.database.relation.DoubleRelation;
+import de.lmu.ifi.dbs.elki.database.relation.MaterializedDoubleRelation;
+import de.lmu.ifi.dbs.elki.database.relation.Relation;
+import de.lmu.ifi.dbs.elki.logging.Logging;
+import de.lmu.ifi.dbs.elki.result.Result;
+import de.lmu.ifi.dbs.elki.result.outlier.OutlierResult;
+import de.lmu.ifi.dbs.elki.result.outlier.OutlierScoreMeta;
+import de.lmu.ifi.dbs.elki.result.outlier.ProbabilisticOutlierScore;
+import de.lmu.ifi.dbs.elki.utilities.ClassGenericsUtil;
+import de.lmu.ifi.dbs.elki.utilities.datastructures.hierarchy.Hierarchy.Iter;
+import de.lmu.ifi.dbs.elki.utilities.documentation.Description;
+import de.lmu.ifi.dbs.elki.utilities.documentation.Title;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.AbstractParameterizer;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameterization.Parameterization;
+
+/**
+ * outlier detection algorithm using EM Clustering. If an object does not belong
+ * to any cluster it is supposed to be an outlier. If the probability for an
+ * object to belong to the most probable cluster is still relatively low this
+ * object is an outlier.
+ *
+ * @author Lisa Reichert
+ *
+ * @apiviz.has EM
+ *
+ * @param <V> Vector type
+ */
+// TODO: re-use an existing EM when present?
+@Title("EM Outlier: Outlier Detection based on the generic EM clustering")
+@Description("The outlier score assigned is based on the highest cluster probability obtained from EM clustering.")
+public class EMOutlier<V extends NumberVector> extends AbstractAlgorithm<OutlierResult> implements OutlierAlgorithm {
+ /**
+ * The logger for this class.
+ */
+ private static final Logging LOG = Logging.getLogger(EMOutlier.class);
+
+ /**
+ * Inner algorithm.
+ */
+ private EM<V, ?> emClustering;
+
+ /**
+ * Constructor with an existing em clustering algorithm.
+ *
+ * @param emClustering EM clustering algorithm to use.
+ */
+ public EMOutlier(EM<V, ?> emClustering) {
+ super();
+ this.emClustering = emClustering;
+ }
+
+ /**
+ * Runs the algorithm in the timed evaluation part.
+ *
+ * @param database Database to process
+ * @param relation Relation to process
+ * @return Outlier result
+ */
+ public OutlierResult run(Database database, Relation<V> relation) {
+ emClustering.setSoft(true);
+ Clustering<?> emresult = emClustering.run(database, relation);
+ Relation<double[]> soft = null;
+ for(Iter<Result> iter = emresult.getHierarchy().iterChildren(emresult); iter.valid(); iter.advance()) {
+ if(!(iter.get() instanceof Relation)) {
+ continue;
+ }
+ if(((Relation<?>) iter.get()).getDataTypeInformation() == EM.SOFT_TYPE) {
+ @SuppressWarnings("unchecked")
+ Relation<double[]> rel = (Relation<double[]>) iter.get();
+ soft = rel;
+ }
+ }
+
+ double globmax = 0.0;
+ WritableDoubleDataStore emo_score = DataStoreUtil.makeDoubleStorage(relation.getDBIDs(), DataStoreFactory.HINT_TEMP | DataStoreFactory.HINT_HOT);
+ for(DBIDIter iditer = relation.iterDBIDs(); iditer.valid(); iditer.advance()) {
+ double maxProb = Double.POSITIVE_INFINITY;
+ double[] probs = soft.get(iditer);
+ for(double prob : probs) {
+ maxProb = Math.min(1. - prob, maxProb);
+ }
+ emo_score.putDouble(iditer, maxProb);
+ globmax = Math.max(maxProb, globmax);
+ }
+ DoubleRelation scoreres = new MaterializedDoubleRelation("EM outlier scores", "em-outlier", emo_score, relation.getDBIDs());
+ OutlierScoreMeta meta = new ProbabilisticOutlierScore(0.0, globmax);
+ // combine results.
+ OutlierResult result = new OutlierResult(meta, scoreres);
+ // TODO: add a keep-EM flag?
+ result.addChildResult(emresult);
+ return result;
+ }
+
+ @Override
+ public TypeInformation[] getInputTypeRestriction() {
+ return TypeUtil.array(TypeUtil.NUMBER_VECTOR_FIELD);
+ }
+
+ @Override
+ protected Logging getLogger() {
+ return LOG;
+ }
+
+ /**
+ * Parameterization class.
+ *
+ * @author Erich Schubert
+ *
+ * @apiviz.exclude
+ */
+ public static class Parameterizer<V extends NumberVector> extends AbstractParameterizer {
+ /**
+ * EM clustering algorithm to run.
+ */
+ protected EM<V, ?> em;
+
+ @Override
+ protected void makeOptions(Parameterization config) {
+ super.makeOptions(config);
+ Class<EM<V, ?>> cls = ClassGenericsUtil.uglyCastIntoSubclass(EM.class);
+ em = config.tryInstantiate(cls);
+ }
+
+ @Override
+ protected EMOutlier<V> makeInstance() {
+ return new EMOutlier<>(em);
+ }
+ }
+}