diff options
author | Andrej Shadura <andrewsh@debian.org> | 2019-03-09 22:30:38 +0000 |
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committer | Andrej Shadura <andrewsh@debian.org> | 2019-03-09 22:30:38 +0000 |
commit | 14a486343aef55f97f54082d6b542dedebf6f3ba (patch) | |
tree | 000fcc4968578771ad265079eef7617d66de2cda /src/de/lmu/ifi/dbs/elki/distance/similarityfunction/kernel/RadialBasisFunctionKernelFunction.java | |
parent | 8300861dc4c62c5567a4e654976072f854217544 (diff) |
Import Upstream version 0.6.0
Diffstat (limited to 'src/de/lmu/ifi/dbs/elki/distance/similarityfunction/kernel/RadialBasisFunctionKernelFunction.java')
-rw-r--r-- | src/de/lmu/ifi/dbs/elki/distance/similarityfunction/kernel/RadialBasisFunctionKernelFunction.java | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/distance/similarityfunction/kernel/RadialBasisFunctionKernelFunction.java b/src/de/lmu/ifi/dbs/elki/distance/similarityfunction/kernel/RadialBasisFunctionKernelFunction.java new file mode 100644 index 00000000..a7613a78 --- /dev/null +++ b/src/de/lmu/ifi/dbs/elki/distance/similarityfunction/kernel/RadialBasisFunctionKernelFunction.java @@ -0,0 +1,102 @@ +package de.lmu.ifi.dbs.elki.distance.similarityfunction.kernel; + +/* + This file is part of ELKI: + Environment for Developing KDD-Applications Supported by Index-Structures + + Copyright (C) 2013 + 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.distance.distancefunction.AbstractVectorDoubleDistanceFunction; +import de.lmu.ifi.dbs.elki.distance.similarityfunction.AbstractVectorDoubleSimilarityFunction; +import de.lmu.ifi.dbs.elki.utilities.Alias; +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.constraints.CommonConstraints; +import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameterization.Parameterization; +import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.DoubleParameter; + +/** + * Provides the Gaussian radial basis function kernel (RBF Kernel). + * + * @author Erich Schubert + */ +@Alias({ "rbf" }) +public class RadialBasisFunctionKernelFunction extends AbstractVectorDoubleSimilarityFunction { + /** + * Scaling factor gamma. (= - 1/(2sigma^2)) + */ + private final double gamma; + + /** + * Constructor. + * + * @param sigma Scaling parameter sigma + */ + public RadialBasisFunctionKernelFunction(double sigma) { + super(); + this.gamma = -.5 / (sigma * sigma); + } + + @Override + public double doubleSimilarity(NumberVector<?> o1, NumberVector<?> o2) { + final int dim = AbstractVectorDoubleDistanceFunction.dimensionality(o1, o2); + double sim = 0.; + for(int i = 0; i < dim; i++) { + final double v = o1.doubleValue(i) - o2.doubleValue(i); + sim += v * v; + } + return Math.exp(gamma * sim); + } + + /** + * Parameterization class. + * + * @author Erich Schubert + * + * @apiviz.exclude + */ + public static class Parameterizer extends AbstractParameterizer { + /** + * Sigma parameter: standard deviation. + */ + public static final OptionID SIGMA_ID = new OptionID("kernel.rbf.sigma", "Standard deviation of the Gaussian RBF kernel."); + + /** + * Sigma parameter + */ + protected double sigma = 1.; + + @Override + protected void makeOptions(Parameterization config) { + super.makeOptions(config); + final DoubleParameter sigmaP = new DoubleParameter(SIGMA_ID, 1.); + sigmaP.addConstraint(CommonConstraints.GREATER_THAN_ZERO_DOUBLE); + if(config.grab(sigmaP)) { + sigma = sigmaP.doubleValue(); + } + } + + @Override + protected RadialBasisFunctionKernelFunction makeInstance() { + return new RadialBasisFunctionKernelFunction(sigma); + } + } +} |