[Insight-users] how to template the image dimension or vector dimesion in template function

[Andreas Schuh]

Hi Baoyun,

use the static constant itk::Vector::Dimension instead.

typedef typename itk::Vector< double, VectorPixelType::Dimension > 
MeasurementVectorType;

itk::Vector::GetVectorDimension() is a static method that has to be 
evaluated at runtime to get the number of components. For template 
arguments you need constant values that can be derived at compile time. 
itk::Vector::Dimension, therefore, is a public static const class 
member, instead.

--
regards
Andreas

Baoyun Li schrieb:
> Dear Andreas and all:
>  
> Can you please teach me how to template the image dimension or vector 
> dimesion in template function.
>  
> In the following template function, if I give the vector dimension as
>  
> typedef typename itk::Vector< double,NumberOfComponents> 
> MeasurementVectorType;
> where Numberof compoents is obtained as trait
> const unsigned int 
> NumberOfComponents=VectorPixelType::GetVectorDimension();
>  
> The program cannot be build.
>  
> Why and how to solve the problem?
>  
> Thanks
>  
> Baoyun
>  
>  
> template <unsigned int Dim,unsigned int NumberOfComponents1,class 
> TInputFilter,  class TOutputFilter>
> void EMClustering( typename TInputFilter::Pointer& inputfilter, 
> typename TOutputFilter::Pointer& outputfilter)
> {
>    typedef typename TInputFilter::PixelType VectorPixelType;
>    typedef typename TInputFilter::PixelType::SizeType Num;
>    const unsigned int 
> NumberOfComponents=VectorPixelType::GetVectorDimension();
>    const unsigned int Dim1=TInputFilter::GetImageDimension();
>   
>   typedef typename itk::Vector< double,NumberOfComponents> 
> MeasurementVectorType;
>   typedef typename itk::Statistics::ListSample< MeasurementVectorType 
> > SampleType;
>  // SampleType::Pointer sample = SampleType::New();
>  // sample->SetMeasurementVectorSize(NumberOfComponents );
>  // MeasurementVectorType mv;
>  
> };
>> ml>
>