source: trunk/sources/HeuristicLab.ExtLibs/HeuristicLab.LibSVM/1.6.3/LibSVM-1.6.3/Scaling.cs @ 5510

/*
 * SVM.NET Library
 * Copyright (C) 2008 Matthew Johnson
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */



namespace SVM {
  /// <summary>
  /// Deals with the scaling of Problems so they have uniform ranges across all dimensions in order to
  /// result in better SVM performance.
  /// </summary>
  public static class Scaling {
    /// <summary>
    /// Scales a problem using the provided range.  This will not affect the parameter.
    /// </summary>
    /// <param name="prob">The problem to scale</param>
    /// <param name="range">The Range transform to use in scaling</param>
    /// <returns>The Scaled problem</returns>
    public static Problem Scale(this IRangeTransform range, Problem prob) {
      Problem scaledProblem = new Problem(prob.Count, new double[prob.Count], new Node[prob.Count][], prob.MaxIndex);
      for (int i = 0; i < scaledProblem.Count; i++) {
        scaledProblem.X[i] = new Node[prob.X[i].Length];
        for (int j = 0; j < scaledProblem.X[i].Length; j++)
          scaledProblem.X[i][j] = new Node(prob.X[i][j].Index, range.Transform(prob.X[i][j].Value, prob.X[i][j].Index));
        scaledProblem.Y[i] = prob.Y[i];
      }
      return scaledProblem;
    }
  }
}