cosine_tree.hpp

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#ifndef MLPACK_CORE_TREE_COSINE_TREE_COSINE_TREE_HPP
#define MLPACK_CORE_TREE_COSINE_TREE_COSINE_TREE_HPP

#include <mlpack/prereqs.hpp>
#include <boost/heap/priority_queue.hpp>

namespace mlpack {
namespace tree {

// Predeclare classes for CosineNodeQueue typedef.
class CompareCosineNode;
class CosineTree;

// CosineNodeQueue typedef.
typedef boost::heap::priority_queue<CosineTree*,
    boost::heap::compare<CompareCosineNode> > CosineNodeQueue;

class CosineTree
{
 public:
  CosineTree(const arma::mat& dataset);

  CosineTree(CosineTree& parentNode, const std::vector<size_t>& subIndices);

  CosineTree(const arma::mat& dataset,
             const double epsilon,
             const double delta);

  ~CosineTree();

  void ModifiedGramSchmidt(CosineNodeQueue& treeQueue,
                           arma::vec& centroid,
                           arma::vec& newBasisVector,
                           arma::vec* addBasisVector = NULL);

  double MonteCarloError(CosineTree* node,
                         CosineNodeQueue& treeQueue,
                         arma::vec* addBasisVector1 = NULL,
                         arma::vec* addBasisVector2 = NULL);

  void ConstructBasis(CosineNodeQueue& treeQueue);

  void CosineNodeSplit();

  void ColumnSamplesLS(std::vector<size_t>& sampledIndices,
                       arma::vec& probabilities, size_t numSamples);

  size_t ColumnSampleLS();

  size_t BinarySearch(arma::vec& cDistribution, double value, size_t start,
                      size_t end);

  void CalculateCosines(arma::vec& cosines);

  void CalculateCentroid();

  void GetFinalBasis(arma::mat& finalBasis) { finalBasis = basis; }

  const arma::mat& GetDataset() const { return dataset; }

  std::vector<size_t>& VectorIndices() { return indices; }

  void L2Error(const double error) { this->l2Error = error; }
  double L2Error() const { return l2Error; }

  arma::vec& Centroid() { return centroid; }

  void BasisVector(arma::vec& bVector) { this->basisVector = bVector; }

  arma::vec& BasisVector() { return basisVector; }

  CosineTree* Parent() const { return parent; }
  CosineTree*& Parent() { return parent; }

  CosineTree* Left() const { return left; }
  CosineTree*& Left() { return left; }

  CosineTree* Right() const { return right; }
  CosineTree*& Right() { return right; }

  size_t NumColumns() const { return numColumns; }

  double FrobNormSquared() const { return frobNormSquared; }

  size_t SplitPointIndex() const { return indices[splitPointIndex]; }

 private:
  const arma::mat& dataset;
  double delta;
  arma::mat basis;
  CosineTree* parent;
  CosineTree* left;
  CosineTree* right;
  std::vector<size_t> indices;
  arma::vec l2NormsSquared;
  arma::vec centroid;
  arma::vec basisVector;
  size_t splitPointIndex;
  size_t numColumns;
  double l2Error;
  double frobNormSquared;
};

class CompareCosineNode
{
 public:

  // Comparison function for construction of priority queue.
  bool operator() (const CosineTree* a, const CosineTree* b) const
  {
    return a->L2Error() < b->L2Error();
  }
};

} // namespace tree
} // namespace mlpack

#endif