Index: trunk/sources/HeuristicLab.Problems.DataAnalysis/3.4/Implementation/Classification/ClassificationSolutionVariableImpactsCalculator.cs
===================================================================
--- trunk/sources/HeuristicLab.Problems.DataAnalysis/3.4/Implementation/Classification/ClassificationSolutionVariableImpactsCalculator.cs	(revision 15638)
+++ trunk/sources/HeuristicLab.Problems.DataAnalysis/3.4/Implementation/Classification/ClassificationSolutionVariableImpactsCalculator.cs	(revision 15638)
@@ -0,0 +1,282 @@
+﻿#region License Information
+
+/* HeuristicLab
+ * Copyright (C) 2002-2018 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 HeuristicLab.Common;
+using HeuristicLab.Core;
+using HeuristicLab.Data;
+using HeuristicLab.Parameters;
+using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
+using HeuristicLab.Random;
+
+namespace HeuristicLab.Problems.DataAnalysis {
+  [StorableClass]
+  [Item("ClassificationSolution Impacts Calculator", "Calculation of the impacts of input variables for any classification solution")]
+  public sealed class ClassificationSolutionVariableImpactsCalculator : ParameterizedNamedItem {
+    public enum ReplacementMethodEnum {
+      Median,
+      Average,
+      Shuffle,
+      Noise
+    }
+    public enum FactorReplacementMethodEnum {
+      Best,
+      Mode,
+      Shuffle
+    }
+    public enum DataPartitionEnum {
+      Training,
+      Test,
+      All
+    }
+
+    private const string ReplacementParameterName = "Replacement Method";
+    private const string DataPartitionParameterName = "DataPartition";
+
+    public IFixedValueParameter<EnumValue<ReplacementMethodEnum>> ReplacementParameter {
+      get { return (IFixedValueParameter<EnumValue<ReplacementMethodEnum>>)Parameters[ReplacementParameterName]; }
+    }
+    public IFixedValueParameter<EnumValue<DataPartitionEnum>> DataPartitionParameter {
+      get { return (IFixedValueParameter<EnumValue<DataPartitionEnum>>)Parameters[DataPartitionParameterName]; }
+    }
+
+    public ReplacementMethodEnum ReplacementMethod {
+      get { return ReplacementParameter.Value.Value; }
+      set { ReplacementParameter.Value.Value = value; }
+    }
+    public DataPartitionEnum DataPartition {
+      get { return DataPartitionParameter.Value.Value; }
+      set { DataPartitionParameter.Value.Value = value; }
+    }
+
+
+    [StorableConstructor]
+    private ClassificationSolutionVariableImpactsCalculator(bool deserializing) : base(deserializing) { }
+    private ClassificationSolutionVariableImpactsCalculator(ClassificationSolutionVariableImpactsCalculator original, Cloner cloner)
+      : base(original, cloner) { }
+    public override IDeepCloneable Clone(Cloner cloner) {
+      return new ClassificationSolutionVariableImpactsCalculator(this, cloner);
+    }
+
+    public ClassificationSolutionVariableImpactsCalculator()
+      : base() {
+      Parameters.Add(new FixedValueParameter<EnumValue<ReplacementMethodEnum>>(ReplacementParameterName, "The replacement method for variables during impact calculation.", new EnumValue<ReplacementMethodEnum>(ReplacementMethodEnum.Median)));
+      Parameters.Add(new FixedValueParameter<EnumValue<DataPartitionEnum>>(DataPartitionParameterName, "The data partition on which the impacts are calculated.", new EnumValue<DataPartitionEnum>(DataPartitionEnum.Training)));
+    }
+
+    //mkommend: annoying name clash with static method, open to better naming suggestions
+    public IEnumerable<Tuple<string, double>> Calculate(IClassificationSolution solution) {
+      return CalculateImpacts(solution, DataPartition, ReplacementMethod);
+    }
+
+    public static IEnumerable<Tuple<string, double>> CalculateImpacts(
+      IClassificationSolution solution,
+      DataPartitionEnum data = DataPartitionEnum.Training,
+      ReplacementMethodEnum replacementMethod = ReplacementMethodEnum.Median,
+      FactorReplacementMethodEnum factorReplacementMethod = FactorReplacementMethodEnum.Best) {
+
+      var problemData = solution.ProblemData;
+      var dataset = problemData.Dataset;
+
+      IEnumerable<int> rows;
+      IEnumerable<double> targetValues;
+      double originalAccuracy;
+
+      OnlineCalculatorError error;
+
+      switch (data) {
+        case DataPartitionEnum.All:
+          rows = problemData.AllIndices;
+          targetValues = problemData.Dataset.GetDoubleValues(problemData.TargetVariable, problemData.AllIndices).ToList();
+          originalAccuracy = OnlineAccuracyCalculator.Calculate(targetValues, solution.EstimatedClassValues, out error);
+          if (error != OnlineCalculatorError.None) throw new InvalidOperationException("Error during accuracy calculation.");
+          break;
+        case DataPartitionEnum.Training:
+          rows = problemData.TrainingIndices;
+          targetValues = problemData.Dataset.GetDoubleValues(problemData.TargetVariable, problemData.TrainingIndices).ToList();
+          originalAccuracy = OnlineAccuracyCalculator.Calculate(targetValues, solution.EstimatedTrainingClassValues, out error);
+          if (error != OnlineCalculatorError.None) throw new InvalidOperationException("Error during accuracy calculation.");
+          break;
+        case DataPartitionEnum.Test:
+          rows = problemData.TestIndices;
+          targetValues = problemData.Dataset.GetDoubleValues(problemData.TargetVariable, problemData.TestIndices).ToList();
+          originalAccuracy = OnlineAccuracyCalculator.Calculate(targetValues, solution.EstimatedTestClassValues, out error);
+          if (error != OnlineCalculatorError.None) throw new InvalidOperationException("Error during accuracy calculation.");
+          break;
+        default: throw new ArgumentException(string.Format("DataPartition {0} cannot be handled.", data));
+      }
+
+      var impacts = new Dictionary<string, double>();
+      var modifiableDataset = ((Dataset)dataset).ToModifiable();
+
+      var inputvariables = new HashSet<string>(problemData.AllowedInputVariables.Union(solution.Model.VariablesUsedForPrediction));
+      var allowedInputVariables = dataset.VariableNames.Where(v => inputvariables.Contains(v)).ToList();
+
+      // calculate impacts for double variables
+      foreach (var inputVariable in allowedInputVariables.Where(problemData.Dataset.VariableHasType<double>)) {
+        var newEstimates = EvaluateModelWithReplacedVariable(solution.Model, inputVariable, modifiableDataset, rows, replacementMethod);
+        var newAccuracy = OnlineAccuracyCalculator.Calculate(targetValues, newEstimates, out error);
+        if (error != OnlineCalculatorError.None) throw new InvalidOperationException("Error during R² calculation with replaced inputs.");
+
+        impacts[inputVariable] = originalAccuracy - newAccuracy;
+      }
+
+      // calculate impacts for string variables
+      foreach (var inputVariable in allowedInputVariables.Where(problemData.Dataset.VariableHasType<string>)) {
+        if (factorReplacementMethod == FactorReplacementMethodEnum.Best) {
+          // try replacing with all possible values and find the best replacement value
+          var smallestImpact = double.PositiveInfinity;
+          foreach (var repl in problemData.Dataset.GetStringValues(inputVariable, rows).Distinct()) {
+            var newEstimates = EvaluateModelWithReplacedVariable(solution.Model, inputVariable, modifiableDataset, rows,
+              Enumerable.Repeat(repl, dataset.Rows));
+            var newAccuracy = OnlineAccuracyCalculator.Calculate(targetValues, newEstimates, out error);
+            if (error != OnlineCalculatorError.None)
+              throw new InvalidOperationException("Error during accuracy calculation with replaced inputs.");
+
+            var impact = originalAccuracy - newAccuracy;
+            if (impact < smallestImpact) smallestImpact = impact;
+          }
+          impacts[inputVariable] = smallestImpact;
+        } else {
+          // for replacement methods shuffle and mode
+          // calculate impacts for factor variables
+
+          var newEstimates = EvaluateModelWithReplacedVariable(solution.Model, inputVariable, modifiableDataset, rows,
+            factorReplacementMethod);
+          var newAccuracy = OnlineAccuracyCalculator.Calculate(targetValues, newEstimates, out error);
+          if (error != OnlineCalculatorError.None)
+            throw new InvalidOperationException("Error during accuracy calculation with replaced inputs.");
+
+          impacts[inputVariable] = originalAccuracy - newAccuracy;
+        }
+      } // foreach
+      return impacts.OrderByDescending(i => i.Value).Select(i => Tuple.Create(i.Key, i.Value));
+    }
+
+    private static IEnumerable<double> EvaluateModelWithReplacedVariable(IClassificationModel model, string variable, ModifiableDataset dataset, IEnumerable<int> rows, ReplacementMethodEnum replacement = ReplacementMethodEnum.Median) {
+      var originalValues = dataset.GetReadOnlyDoubleValues(variable).ToList();
+      double replacementValue;
+      List<double> replacementValues;
+      IRandom rand;
+
+      switch (replacement) {
+        case ReplacementMethodEnum.Median:
+          replacementValue = rows.Select(r => originalValues[r]).Median();
+          replacementValues = Enumerable.Repeat(replacementValue, dataset.Rows).ToList();
+          break;
+        case ReplacementMethodEnum.Average:
+          replacementValue = rows.Select(r => originalValues[r]).Average();
+          replacementValues = Enumerable.Repeat(replacementValue, dataset.Rows).ToList();
+          break;
+        case ReplacementMethodEnum.Shuffle:
+          // new var has same empirical distribution but the relation to y is broken
+          rand = new FastRandom(31415);
+          // prepare a complete column for the dataset
+          replacementValues = Enumerable.Repeat(double.NaN, dataset.Rows).ToList();
+          // shuffle only the selected rows
+          var shuffledValues = rows.Select(r => originalValues[r]).Shuffle(rand).ToList();
+          int i = 0;
+          // update column values 
+          foreach (var r in rows) {
+            replacementValues[r] = shuffledValues[i++];
+          }
+          break;
+        case ReplacementMethodEnum.Noise:
+          var avg = rows.Select(r => originalValues[r]).Average();
+          var stdDev = rows.Select(r => originalValues[r]).StandardDeviation();
+          rand = new FastRandom(31415);
+          // prepare a complete column for the dataset
+          replacementValues = Enumerable.Repeat(double.NaN, dataset.Rows).ToList();
+          // update column values 
+          foreach (var r in rows) {
+            replacementValues[r] = NormalDistributedRandom.NextDouble(rand, avg, stdDev);
+          }
+          break;
+
+        default:
+          throw new ArgumentException(string.Format("ReplacementMethod {0} cannot be handled.", replacement));
+      }
+
+      return EvaluateModelWithReplacedVariable(model, variable, dataset, rows, replacementValues);
+    }
+
+    private static IEnumerable<double> EvaluateModelWithReplacedVariable(
+      IClassificationModel model, string variable, ModifiableDataset dataset,
+      IEnumerable<int> rows,
+      FactorReplacementMethodEnum replacement = FactorReplacementMethodEnum.Shuffle) {
+      var originalValues = dataset.GetReadOnlyStringValues(variable).ToList();
+      List<string> replacementValues;
+      IRandom rand;
+
+      switch (replacement) {
+        case FactorReplacementMethodEnum.Mode:
+          var mostCommonValue = rows.Select(r => originalValues[r])
+            .GroupBy(v => v)
+            .OrderByDescending(g => g.Count())
+            .First().Key;
+          replacementValues = Enumerable.Repeat(mostCommonValue, dataset.Rows).ToList();
+          break;
+        case FactorReplacementMethodEnum.Shuffle:
+          // new var has same empirical distribution but the relation to y is broken
+          rand = new FastRandom(31415);
+          // prepare a complete column for the dataset
+          replacementValues = Enumerable.Repeat(string.Empty, dataset.Rows).ToList();
+          // shuffle only the selected rows
+          var shuffledValues = rows.Select(r => originalValues[r]).Shuffle(rand).ToList();
+          int i = 0;
+          // update column values 
+          foreach (var r in rows) {
+            replacementValues[r] = shuffledValues[i++];
+          }
+          break;
+        default:
+          throw new ArgumentException(string.Format("FactorReplacementMethod {0} cannot be handled.", replacement));
+      }
+
+      return EvaluateModelWithReplacedVariable(model, variable, dataset, rows, replacementValues);
+    }
+
+    private static IEnumerable<double> EvaluateModelWithReplacedVariable(IClassificationModel model, string variable,
+      ModifiableDataset dataset, IEnumerable<int> rows, IEnumerable<double> replacementValues) {
+      var originalValues = dataset.GetReadOnlyDoubleValues(variable).ToList();
+      dataset.ReplaceVariable(variable, replacementValues.ToList());
+      //mkommend: ToList is used on purpose to avoid lazy evaluation that could result in wrong estimates due to variable replacements
+      var estimates = model.GetEstimatedClassValues(dataset, rows).ToList();
+      dataset.ReplaceVariable(variable, originalValues);
+
+      return estimates;
+    }
+    private static IEnumerable<double> EvaluateModelWithReplacedVariable(IClassificationModel model, string variable,
+      ModifiableDataset dataset, IEnumerable<int> rows, IEnumerable<string> replacementValues) {
+      var originalValues = dataset.GetReadOnlyStringValues(variable).ToList();
+      dataset.ReplaceVariable(variable, replacementValues.ToList());
+      //mkommend: ToList is used on purpose to avoid lazy evaluation that could result in wrong estimates due to variable replacements
+      var estimates = model.GetEstimatedClassValues(dataset, rows).ToList();
+      dataset.ReplaceVariable(variable, originalValues);
+
+      return estimates;
+    }
+  }
+}
