kernel_pca_impl.hpp

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#ifndef MLPACK_METHODS_KERNEL_PCA_KERNEL_PCA_IMPL_HPP
#define MLPACK_METHODS_KERNEL_PCA_KERNEL_PCA_IMPL_HPP

// In case it hasn't already been included.
#include "kernel_pca.hpp"

namespace mlpack {
namespace kpca {

template <typename KernelType, typename KernelRule>
KernelPCA<KernelType, KernelRule>::KernelPCA(const KernelType kernel,
                                 const bool centerTransformedData) :
      kernel(kernel),
      centerTransformedData(centerTransformedData)
{ }

template <typename KernelType, typename KernelRule>
void KernelPCA<KernelType, KernelRule>::Apply(const arma::mat& data,
                                  arma::mat& transformedData,
                                  arma::vec& eigval,
                                  arma::mat& eigvec,
                                  const size_t newDimension)
{
  KernelRule::ApplyKernelMatrix(data, transformedData, eigval,
                                eigvec, newDimension, kernel);

  // Center the transformed data, if the user asked for it.
  if (centerTransformedData)
  {
    arma::colvec transformedDataMean = arma::mean(transformedData, 1);
    transformedData = transformedData - (transformedDataMean *
        arma::ones<arma::rowvec>(transformedData.n_cols));
  }
}

template <typename KernelType, typename KernelRule>
void KernelPCA<KernelType, KernelRule>::Apply(const arma::mat& data,
                                  arma::mat& transformedData,
                                  arma::vec& eigval,
                                  arma::mat& eigvec)
{
  Apply(data, transformedData, eigval, eigvec, data.n_cols);
}

template <typename KernelType, typename KernelRule>
void KernelPCA<KernelType, KernelRule>::Apply(const arma::mat& data,
                                  arma::mat& transformedData,
                                  arma::vec& eigVal)
{
  arma::mat coeffs;
  Apply(data, transformedData, eigVal, coeffs, data.n_cols);
}

template <typename KernelType, typename KernelRule>
void KernelPCA<KernelType, KernelRule>::Apply(arma::mat& data,
                                    const size_t newDimension)
{
  arma::mat coeffs;
  arma::vec eigVal;

  Apply(data, data, eigVal, coeffs, newDimension);

  if (newDimension < coeffs.n_rows && newDimension > 0)
    data.shed_rows(newDimension, data.n_rows - 1);
}

} // namespace kpca
} // namespace mlpack

#endif