source: branches/DataPreprocessing/HeuristicLab.DataPreprocessing/3.4/PreprocessingTransformator.cs @ 10967

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2013 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab 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.
 *
 * HeuristicLab 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 HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using HeuristicLab.Data;
using HeuristicLab.Problems.DataAnalysis.Transformations;

namespace HeuristicLab.DataPreprocessing {
  public class PreprocessingTransformator {
    private readonly ITransactionalPreprocessingData preprocessingData;

    private readonly IDictionary<string, IList<double>> originalColumns;

    public PreprocessingTransformator(IPreprocessingData preprocessingData) {
      this.preprocessingData = (ITransactionalPreprocessingData)preprocessingData;
      originalColumns = new Dictionary<string, IList<double>>();
    }

    public bool ApplyTransformations(IEnumerable<ITransformation> transformations, bool preserveColumns, out string errorMsg) {
      bool success;

      preprocessingData.BeginTransaction(DataPreprocessingChangedEventType.Transformation);
      try {
        var doubleTransformations = transformations.OfType<Transformation<double>>().ToList();
        ApplyDoubleTranformations(doubleTransformations, preserveColumns, out success, out errorMsg);

        if (preserveColumns) {
          RestorePreservedColumns(doubleTransformations);
          originalColumns.Clear();
        }
      } finally {
        preprocessingData.EndTransaction();
      }

      return success;
    }

    private void ApplyDoubleTranformations(IList<Transformation<double>> transformations, bool preserveColumns, out bool success, out string errorMsg) {
      errorMsg = string.Empty;
      success = true;
      foreach (var transformation in transformations) {
        int colIndex = preprocessingData.GetColumnIndex(transformation.Column);

        var originalData = preprocessingData.GetValues<double>(colIndex);

        if (preserveColumns && !originalColumns.ContainsKey(transformation.Column))
          originalColumns.Add(transformation.Column, originalData);

        string errorMsgPart;
        bool successPart;
        var transformedData = ApplyDoubleTransformation(transformation, originalData, out successPart, out errorMsgPart);
        errorMsg += errorMsgPart + Environment.NewLine;

        if (!successPart) success = false;
        preprocessingData.SetValues(colIndex, transformedData.ToList());
        preprocessingData.Transformations.Add(transformation);
      }
    }

    private IEnumerable<double> ApplyDoubleTransformation(Transformation<double> transformation, IList<double> data, out bool success, out string errorMsg) {
      success = transformation.Check(data, out errorMsg);
      return transformation.Apply(data);
    }

    private void RestorePreservedColumns(IList<Transformation<double>> transformations) {
      foreach (var column in originalColumns) {
        int originalColumnIndex = preprocessingData.GetColumnIndex(column.Key);
        int newColumnIndex = originalColumnIndex + 1;
        string newColumnName = GetTransformatedColumnName(transformations, column.Key);

        // create new transformed column
        preprocessingData.InsertColumn<double>(newColumnName, newColumnIndex);
        preprocessingData.SetValues(newColumnIndex, preprocessingData.GetValues<double>(originalColumnIndex));
        // restore old values
        preprocessingData.SetValues(originalColumnIndex, column.Value);
      }
    }

    private string GetTransformatedColumnName(IList<Transformation<double>> transformations, string column) {
      string suffix = GetTransformationSuffix(transformations, column);
      return column + "_" + suffix;
    }

    private string GetTransformationSuffix(IList<Transformation<double>> transformations, string column) {
      var suffixes = transformations.Where(t => t.Column == column).Select(t => t.ShortName);
      var builder = new StringBuilder();
      foreach (var suffix in suffixes) {
        builder.Append(suffix);
      }
      return builder.ToString();
    }
  }
}