NullReferenceException in SymbolicRegressionScaledMeanSquaredErrorEvaluator

[gkronber]

This also affects SymbolicRegressionScaledMeanAndVarianceSquaredErrorEvaluator.

OperatorExecutionException: An exception was thrown by the operator
"FixedValidationBestScaledSymbolicRegressionSolutionAnalyzer": Object reference not set to an instance of an object.

-----
NullReferenceException: Object reference not set to an instance of an object.
    at HeuristicLab.Parameters.LookupParameter`1.LookupVariable(String name)
    at HeuristicLab.Parameters.LookupParameter`1.GetActualValue()
    at HeuristicLab.Parameters.LookupParameter`1.get_ActualValue()
    at
HeuristicLab.Problems.DataAnalysis.Regression.Symbolic.SymbolicRegressionScaledMeanAndVarianceSquaredErrorEvaluator.Evaluate(ISymbolicExpressionTreeInterpreter
interpreter, SymbolicExpressionTree solution, Double lowerEstimationLimit, Double upperEstimationLimit, Dataset dataset, String targetVariable, IEnumerable`1 rows)
    at
HeuristicLab.Problems.DataAnalysis.Regression.Symbolic.Analyzers.FixedValidationBestScaledSymbolicRegressionSolutionAnalyzer.Apply()
    at HeuristicLab.Operators.Operator.Execute(IExecutionContext context)
    at HeuristicLab.SequentialEngine.SequentialEngine.ProcessNextOperation()


--------------------------------------------------------------------------

OperatorExecutionException: An exception was thrown by the operator
"FixedValidationBestScaledSymbolicRegressionSolutionAnalyzer": Object reference not set to an instance of an object.

-----
NullReferenceException: Object reference not set to an instance of an object.
    at HeuristicLab.Parameters.LookupParameter`1.LookupVariable(String name)
    at HeuristicLab.Parameters.LookupParameter`1.SetActualValue(IItem value)
    at HeuristicLab.Parameters.LookupParameter`1.set_ActualValue(T value)
    at
HeuristicLab.Problems.DataAnalysis.Regression.Symbolic.SymbolicRegressionScaledMeanSquaredErrorEvaluator.Evaluate(ISymbolicExpressionTreeInterpreter
interpreter, SymbolicExpressionTree solution, Double lowerEstimationLimit, Double upperEstimationLimit, Dataset dataset, String targetVariable, IEnumerable`1 rows)
    at
HeuristicLab.Problems.DataAnalysis.Regression.Symbolic.Analyzers.FixedValidationBestScaledSymbolicRegressionSolutionAnalyzer.Apply()
    at HeuristicLab.Operators.Operator.Execute(IExecutionContext context)
    at HeuristicLab.SequentialEngine.SequentialEngine.ProcessNextOperation()

[mkommend]

Added check for ExecutionContext in scaled evaluators with r5169.

[gkronber]

Reviewed changeset r5169. Checking if the ExecutionContext is set before writing parameter values definitely works even though it is a bit awkward. These two operators should not be used anymore because they have been superseded by evaluation based on the squared correlation coefficient and it is likely that these two classes will be removed in the planned refactoring of the data-analysis plugins.

As the bug has been fixed successfully with r5169 I set the status ticket to ready to release. The issue should be reconsidered in the refactoring phase of the data-analysis plugins.