[Insight-developers] ItkNeuralNetworkIOTest

[Hans J. Johnson]

Raghu,

I am attempting to use the ITK neural network IO classes that you have
graciously provided. I am, however, getting segmentation faults when my
network is the specialization for a
OneHiddenLayerBackPropagationNeuralNetwork, and I can not read a saved file
into .  

I¹ve added the following code to the very end of itkNeuralNetworkIOTest.cxx
in an attempt to figure out what is going on:

==============================================================
//Now test reading and writing of OneHiddenLayerBackPropagationNeuralNetwork
    {
    typedef 
itk::Statistics::OneHiddenLayerBackPropagationNeuralNetwork<MeasurementVecto
rType, TargetVectorType> OneHiddenLayerBackPropagationNeuralNetworkType;
    OneHiddenLayerBackPropagationNeuralNetworkType::Pointer
OneHiddenLayerNet = OneHiddenLayerBackPropagationNeuralNetworkType::New();
    OneHiddenLayerNet->SetNumOfInputNodes(7);
    OneHiddenLayerNet->SetNumOfHiddenNodes(13);
    OneHiddenLayerNet->SetNumOfOutputNodes(5);

    OneHiddenLayerNet->Initialize();
    OneHiddenLayerNet->InitializeWeights();
    OneHiddenLayerNet->SetLearningRate(0.001);
      {
      WriterType::Pointer
writerOneHiddenLayerBackPropagation=WriterType::New();
      writerOneHiddenLayerBackPropagation->SetWriteWeightValuesType(2);
      
writerOneHiddenLayerBackPropagation->SetFileName("OneHiddenLayerNet.txt");
      writerOneHiddenLayerBackPropagation->SetInput(OneHiddenLayerNet);
      writerOneHiddenLayerBackPropagation->Update();
     //This writing operation causes a segmentation fault at runtime
      }
      {
      ReaderType::Pointer
readerOneHiddenLayerBackPropagation=ReaderType::New();
      readerOneHiddenLayerBackPropagation->SetFileName(
"OneHiddenLayerNet.txt" );
      readerOneHiddenLayerBackPropagation->SetReadWeightValuesType( 1 );
      readerOneHiddenLayerBackPropagation->Update();
      //The following line gives a compiler error
      //OneHiddenLayerBackPropagationNeuralNetworkType::Pointer
OneHiddenLayerNet_ReadIn = readerOneHiddenLayerBackPropagation->GetOutput();
      //Need some type of comparison here
      }
    }
==============================================================

Here is the compiler error:
/scratch/hjohnson/src/brains2/iplFreeware/unpackdir/Insight/Testing/Code/Rev
iew/itkNeuralNetworkIOTest.cxx: In function 'int itkNeuralNetworkIOTest(int,
char**)':
/scratch/hjohnson/src/brains2/iplFreeware/unpackdir/Insight/Testing/Code/Rev
iew/itkNeuralNetworkIOTest.cxx:257: error: invalid conversion from
'itk::Statistics::MultilayerNeuralNetworkBase<itkNeuralNetworkIOTest(int,
char**)::MeasurementVectorType, itkNeuralNetworkIOTest(int,
char**)::TargetVectorType>*' to
'itk::Statistics::OneHiddenLayerBackPropagationNeuralNetwork<itkNeuralNetwor
kIOTest(int, char**)::MeasurementVectorType, itkNeuralNetworkIOTest(int,
char**)::TargetVectorType>*'
/scratch/hjohnson/src/brains2/iplFreeware/unpackdir/Insight/Testing/Code/Rev
iew/itkNeuralNetworkIOTest.cxx:257: error:   initializing argument 1 of
'itk::SmartPointer<TObjectType>::SmartPointer(TObjectType*) [with
TObjectType = 
itk::Statistics::OneHiddenLayerBackPropagationNeuralNetwork<itkNeuralNetwork
IOTest(int, char**)::MeasurementVectorType, itkNeuralNetworkIOTest(int,
char**)::TargetVectorType>]'
make[2]: *** 
[Testing/Code/Review/CMakeFiles/itkReviewTests.dir/itkNeuralNetworkIOTest.o]
Error 1
make[1]: *** [Testing/Code/Review/CMakeFiles/itkReviewTests.dir/all] Error 2
make: *** [all] Error 2

With the compiler error line commented out, the program builds, but a
segmentation fault occurs during runtime.

Perhaps this class could be templated over the network type rather than the
input and output parameter types?  Or does a special IO mechanism need to be
created for each of the Network types?  The
OneHiddenLayerBackPropagationNeuralNetwork is just a special case of a
Multilayer NeuralNetwork, so I thought that the itkNeuralNetworkIO mechansim
should work.

Any help or advice would be greatly appreciated.
Thanks,
Hans
-- 
Hans J. Johnson, Ph.D.
Hans-johnson at uiowa.edu

278 GH
The University of Iowa
Iowa City, IA 52241
(319) 353 8587

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