source: trunk/lib/svm/KernelView.h @ 331

// $Id: KernelView.h 331 2005-06-01 22:06:51Z peter $

#ifndef _theplu_svm_kernel_view_
#define _theplu_svm_kernel_view_

#include <c++_tools/svm/Kernel.h>
#include <vector>

namespace theplu {
namespace svm {

  class KernelFunction;

  ///
  ///   @brief View into sub Kernel
  ///   When training 
  ///
  class KernelView : public Kernel 
  {
    
  public:
    
    ///
    /// Contructor taking the Kernel to view into and a vector of the
    /// indeces we view into. The constructed Kernel matrix will have
    /// dimensions \f$NxN\f$ where \f$N\f$ is the size of \a index. If
    /// Kernel is a KernelView, as now it implemented to view into the
    /// view rather directly into the original Kernel, and may
    /// therefore be slow. Use instead the original Kernel and view
    /// directly into that.
    ///
    KernelView(const Kernel& kernel, const std::vector<size_t>& index);
    
    ///
    /// @todo
    /// Copy constructor
    ///
    KernelView(const KernelView&);

    ///
    ///   Destructor
    ///
    virtual ~KernelView(void);

    ///
    /// @return element at position (\a row, \a column) in the Kernel
    /// matrix
    ///
    inline double operator()(const size_t row,const size_t column) const
    { return (*kernel_)(index_[row],index_[column]); }

    ///
    /// @brief number of samples
    ///
    size_t size(void) const { return index_.size(); } 
    

  private:
    const Kernel* kernel_;
    const std::vector<size_t>& index_;


    inline bool is_view(void) const { return true; }

  }; // class KernelView

}} // of namespace svm and namespace theplu

#endif