source: branches/DataPreprocessing/HeuristicLab.Problems.DataAnalysis.Transformations/3.4/ReciprocalTransformation.cs @ 11064

using System;
using System.Collections.Generic;
using System.Linq;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
namespace HeuristicLab.Problems.DataAnalysis.Transformations {
  [Item("Reciprocal Transformation", "f(x) = 1 / x | Represents a reciprocal transformation.")]
  public class ReciprocalTransformation : Transformation<double> {

    #region properties
    public override string ShortName {
      get { return "Inv"; }
    }
    #endregion

    //TODO: is a special case of Linear
    [StorableConstructor]
    protected ReciprocalTransformation(bool deserializing) : base(deserializing) { }
    protected ReciprocalTransformation(Transformation<double> original, Cloner cloner)
      : base(original, cloner) {
    }
    public ReciprocalTransformation(IEnumerable<string> allowedColumns)
      : base(allowedColumns) {
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new ReciprocalTransformation(this, cloner);
    }

    public override IEnumerable<double> Apply(IEnumerable<double> data) {
      foreach (double i in data) {
        if (i > 0.0)
          yield return 1.0 / i;
        else
          yield return i;
      }
    }

    public override bool Check(IEnumerable<double> data, out string errorMsg) {
      errorMsg = null;
      int errorCounter = data.Count(i => i <= 0.0);
      if (errorCounter > 0) {
        errorMsg = String.Format("{0} values are zero or below zero. 1/x can not be applied onto these values", errorCounter);
        return false;
      }
      return true;
    }
  }
}