.. _program_listing_file_src_function_cpu_ExemplarClusteringSubmodularFunction.h:

Program Listing for File ExemplarClusteringSubmodularFunction.h
===============================================================

|exhale_lsh| :ref:`Return to documentation for file <file_src_function_cpu_ExemplarClusteringSubmodularFunction.h>` (``src/function/cpu/ExemplarClusteringSubmodularFunction.h``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #ifndef EXEMCL_FUNCTION_CPU
   #define EXEMCL_FUNCTION_CPU
   
   #include <src/function/SubmodularFunction.h>
   #include <utility>
   
   namespace exemcl::cpu {
       template<typename HostDataType = float>
       class ExemplarClusteringSubmodularFunction : public SubmodularFunction {
       public:
           using SubmodularFunction::operator();
   
           explicit ExemplarClusteringSubmodularFunction(const MatrixX<HostDataType>& V, int workerCount = -1) :
               SubmodularFunction(workerCount), _V(std::make_unique<MatrixX<HostDataType>>(V)) {
               MatrixX<HostDataType> zeroVec = VectorX<HostDataType>::Zero(_V->cols()).transpose();
               _zeroVecValue = L(zeroVec);
           };
   
           double operator()(const MatrixX<double>& S) override {
               return ((const ExemplarClusteringSubmodularFunction*) (this))->operator()(S);
           };
   
           double operator()(const MatrixX<double>& S) const override {
               auto S_copy = std::make_unique<MatrixX<HostDataType>>(S.cast<HostDataType>());
   
               // Add zero vector to data copy.
               S_copy->conservativeResize(S_copy->rows() + 1, Eigen::NoChange_t());
               S_copy->row(S_copy->rows() - 1).setZero();
   
               // Make calculations.
               HostDataType L_2 = L(*S_copy);
   
               return _zeroVecValue - L_2;
           };
   
           const MatrixX<HostDataType>& getV() const {
               return _V;
           };
   
       private:
           HostDataType _zeroVecValue;
           const std::unique_ptr<MatrixX<HostDataType>> _V;
   
           HostDataType L(const MatrixX<HostDataType>& S_inner) const {
               auto* accuArray = new HostDataType[_V->rows()];
   
               for (unsigned int i = 0; i < _V->rows(); i++) {
                   auto min_val = std::numeric_limits<HostDataType>::max();
                   for (unsigned int j = 0; j < S_inner.rows(); j++)
                       min_val = std::min((_V->row(i) - S_inner.row(j)).squaredNorm(), min_val);
                   accuArray[i] = min_val;
               }
   
               HostDataType accu = 0.0;
   #pragma omp simd reduction(+ : accu)
               for (unsigned int i = 0; i < _V->rows(); i++)
                   accu += accuArray[i];
   
               delete[] accuArray;
               return accu / static_cast<HostDataType>(_V->rows());
           };
       };
   }
   
   #endif // EXEMCL_FUNCTION_CPU