1 files changed, 115 insertions, 0 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/datasource/filter/normalization/LengthNormalization.java b/src/de/lmu/ifi/dbs/elki/datasource/filter/normalization/LengthNormalization.java
new file mode 100644
index 00000000..6de7eaba
--- /dev/null
+++ b/src/de/lmu/ifi/dbs/elki/datasource/filter/normalization/LengthNormalization.java
@@ -0,0 +1,115 @@
+package de.lmu.ifi.dbs.elki.datasource.filter.normalization;
+
+/*
+ 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.data.NumberVector;
+import de.lmu.ifi.dbs.elki.data.type.SimpleTypeInformation;
+import de.lmu.ifi.dbs.elki.data.type.TypeUtil;
+import de.lmu.ifi.dbs.elki.distance.distancefunction.DoubleNorm;
+import de.lmu.ifi.dbs.elki.distance.distancefunction.EuclideanDistanceFunction;
+import de.lmu.ifi.dbs.elki.math.linearalgebra.LinearEquationSystem;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.AbstractParameterizer;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.OptionID;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameterization.Parameterization;
+import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.ObjectParameter;
+
+/**
+ * Class to perform a normalization on vectors to norm 1.
+ * 
+ * @author Heidi Kolb
+ * @author Erich Schubert
+ * 
+ * @param <V> vector type
+ */
+public class LengthNormalization<V extends NumberVector<V, ?>> extends AbstractNormalization<V> {
+  /**
+   * Norm to use
+   */
+  DoubleNorm<? super V> norm;
+
+  /**
+   * Constructor
+   * 
+   * @param norm Norm to use
+   */
+  public LengthNormalization(DoubleNorm<? super V> norm) {
+    super();
+    this.norm = norm;
+  }
+
+  @Override
+  protected V filterSingleObject(V featureVector) {
+    final double d = norm.doubleNorm(featureVector);
+    return featureVector.newNumberVector(featureVector.getColumnVector().timesEquals(1 / d).getArrayRef());
+  }
+
+  @Override
+  public V restore(V featureVector) throws NonNumericFeaturesException {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public LinearEquationSystem transform(LinearEquationSystem linearEquationSystem) {
+    // TODO.
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  protected SimpleTypeInformation<? super V> getInputTypeRestriction() {
+    return TypeUtil.NUMBER_VECTOR_FIELD;
+  }
+
+  /**
+   * Parameterization class.
+   * 
+   * @author Erich Schubert
+   * 
+   * @apiviz.exclude
+   */
+  public static class Parameterizer<V extends NumberVector<V, ?>> extends AbstractParameterizer {
+    /**
+     * Option ID for normalization norm
+     */
+    public static final OptionID NORM_ID = OptionID.getOrCreateOptionID("normalization.norm", "Norm (length function) to use for computing the vector length.");
+
+    /**
+     * Norm to use
+     */
+    DoubleNorm<? super V> norm;
+
+    @Override
+    protected void makeOptions(Parameterization config) {
+      super.makeOptions(config);
+      ObjectParameter<DoubleNorm<? super V>> normP = new ObjectParameter<DoubleNorm<? super V>>(NORM_ID, DoubleNorm.class, EuclideanDistanceFunction.class);
+      if(config.grab(normP)) {
+        norm = normP.instantiateClass(config);
+      }
+    }
+
+    @Override
+    protected LengthNormalization<V> makeInstance() {
+      return new LengthNormalization<V>(norm);
+    }
+  }
+}
+\ No newline at end of file