// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-FileCopyrightText: Copyright 2010 Sandia Corporation
// SPDX-License-Identifier: LicenseRef-BSD-3-Clause-Sandia-USGov
/**
 * @class   vtkKMeansStatistics
 * @brief   A class for KMeans clustering
 *
 *
 * This class takes as input an optional vtkTable on port LEARN_PARAMETERS
 * specifying initial  set(s) of cluster values of the following form:
 * <pre>
 *           K     | Col1            |  ...    | ColN
 *      -----------+-----------------+---------+---------------
 *           M     |clustCoord(1, 1) |  ...    | clustCoord(1, N)
 *           M     |clustCoord(2, 1) |  ...    | clustCoord(2, N)
 *           .     |       .         |   .     |        .
 *           .     |       .         |   .     |        .
 *           .     |       .         |   .     |        .
 *           M     |clustCoord(M, 1) |  ...    | clustCoord(M, N)
 *           L     |clustCoord(1, 1) |  ...    | clustCoord(1, N)
 *           L     |clustCoord(2, 1) |  ...    | clustCoord(2, N)
 *           .     |       .         |   .     |        .
 *           .     |       .         |   .     |        .
 *           .     |       .         |   .     |        .
 *           L     |clustCoord(L, 1) |  ...    | clustCoord(L, N)
 * </pre>
 *
 * Because the desired value of K is often not known in advance and the
 * results of the algorithm are dependent on the initial cluster centers,
 * we provide a mechanism for the user to test multiple runs or sets of cluster centers
 * within a single call to the Learn phase.  The first column of the table identifies
 * the number of clusters K in the particular run (the entries in this column should be
 * of type vtkIdType), while the remaining columns are a
 * subset of the columns contained in the table on port INPUT_DATA.  We require that
 * all user specified clusters be of the same dimension N and consequently, that the
 * LEARN_PARAMETERS table have N+1 columns. Due to this restriction, only one request
 * can be processed for each call to the Learn phase and subsequent requests are
 * silently ignored. Note that, if the first column of the LEARN_PARAMETERS table is not
 * of type vtkIdType, then the table will be ignored and a single run will be performed using
 * the first DefaultNumberOfClusters input data observations as initial cluster centers.
 *
 * When the user does not supply an initial set of clusters, then the first
 * DefaultNumberOfClusters input data observations are used as initial cluster
 * centers and a single run is performed.
 *
 *
 * This class provides the following functionalities, depending on the operation
 * in which it is executed:
 * * Learn: calculates new cluster centers for each run.  The output metadata on
 *   port OUTPUT_MODEL is a multiblock dataset containing at a minimum
 *   one vtkTable with columns specifying the following for each run:
 *   the run ID, number of clusters, number of iterations required for convergence,
 *   total error associated with the cluster (sum of squared Euclidean distance from each
 * observation to its nearest cluster center), the cardinality of the cluster, and the new cluster
 * coordinates.
 *
 * * Derive:  An additional vtkTable is stored in the multiblock dataset output on port
 * OUTPUT_MODEL. This table contains columns that store for each run: the runID, number of clusters,
 *   total error for all clusters in the run, local rank, and global rank.
 *   The local rank is computed by comparing squared Euclidean errors of all runs with
 *   the same number of clusters.  The global rank is computed analagously across all runs.
 *
 * * Assess: This requires a multiblock dataset (as computed from Learn and Derive) on input port
 * INPUT_MODEL and tabular data on input port INPUT_DATA that contains column names matching those
 *   of the tables on input port INPUT_MODEL. The assess mode reports the closest cluster center
 *   and associated squared Euclidean distance of each observation in port INPUT_DATA's table to the
 * cluster centers for each run in the multiblock dataset provided on port INPUT_MODEL.
 *
 * The code can handle a wide variety of data types as it operates on vtkAbstractArrays
 * and is not limited to vtkDataArrays.  A default distance functor that
 * computes the sum of the squares of the Euclidean distance between two objects is provided
 * (vtkKMeansDistanceFunctor). The default distance functor can be overridden to use alternative
 * distance metrics.
 *
 * @par Thanks:
 * Thanks to Janine Bennett, David Thompson, and Philippe Pebay of
 * Sandia National Laboratories for implementing this class.
 * Updated by Philippe Pebay, Kitware SAS 2012
 */

#ifndef vtkKMeansStatistics_h
#define vtkKMeansStatistics_h

#include "vtkFiltersStatisticsModule.h" // For export macro
#include "vtkStatisticsAlgorithm.h"

VTK_ABI_NAMESPACE_BEGIN
class vtkIdTypeArray;
class vtkIntArray;
class vtkDoubleArray;
class vtkKMeansDistanceFunctor;
class vtkStatisticalModel;

class VTKFILTERSSTATISTICS_EXPORT vtkKMeansStatistics : public vtkStatisticsAlgorithm
{
public:
  vtkTypeMacro(vtkKMeansStatistics, vtkStatisticsAlgorithm);
  void PrintSelf(ostream& os, vtkIndent indent) override;
  static vtkKMeansStatistics* New();

  ///@{
  /**
   * Set the DistanceFunctor.
   */
  virtual void SetDistanceFunctor(vtkKMeansDistanceFunctor*);
  vtkGetObjectMacro(DistanceFunctor, vtkKMeansDistanceFunctor);
  ///@}

  ///@{
  /**
   * Set/get the \a DefaultNumberOfClusters, used when no initial cluster coordinates are specified.
   */
  vtkSetMacro(DefaultNumberOfClusters, int);
  vtkGetMacro(DefaultNumberOfClusters, int);
  ///@}

  ///@{
  /**
   * Set/get the KValuesArrayName.
   */
  vtkSetStringMacro(KValuesArrayName);
  vtkGetStringMacro(KValuesArrayName);
  ///@}

  ///@{
  /**
   * Set/get the MaxNumIterations used to terminate iterations on
   * cluster center coordinates when the relative tolerance can not be met.
   */
  vtkSetMacro(MaxNumIterations, int);
  vtkGetMacro(MaxNumIterations, int);
  ///@}

  ///@{
  /**
   * Set/get the relative \a Tolerance used to terminate iterations on
   * cluster center coordinates.
   */
  vtkSetMacro(Tolerance, double);
  vtkGetMacro(Tolerance, double);
  ///@}

  /**
   * Given a collection of models, calculate aggregate model
   * NB: not implemented
   */
  bool Aggregate(vtkDataObjectCollection*, vtkStatisticalModel*) override { return false; }

  /**
   * A convenience method for setting properties by name.
   */
  bool SetParameter(const char* parameter, int index, vtkVariant value) override;

  /// Provide a string that can be used to recreate an instance of this algorithm.
  void AppendAlgorithmParameters(std::string& algorithmParameters) const override;

  /// Implement the inverse of AppendAlgorithmParameters(): given parameters, update this algorithm.
  std::size_t ConsumeNextAlgorithmParameter(
    vtkStringToken parameterName, const std::string& algorithmParameters) override;

protected:
  vtkKMeansStatistics();
  ~vtkKMeansStatistics() override;

  /**
   * Execute the calculations required by the Learn option.
   */
  void Learn(vtkTable*, vtkTable*, vtkStatisticalModel*) override;

  /**
   * Execute the calculations required by the Derive option.
   */
  void Derive(vtkStatisticalModel*) override;

  /**
   * Execute the calculations required by the Assess option.
   */
  void Assess(vtkTable*, vtkStatisticalModel*, vtkTable*) override;

  /**
   * Execute the calculations required by the Test option.
   */
  void Test(vtkTable*, vtkStatisticalModel*, vtkTable*) override {}

  /**
   * Provide the appropriate assessment functor.
   */
  void SelectAssessFunctor(vtkTable* inData, vtkDataObject* inMeta, vtkStringArray* rowNames,
    AssessFunctor*& dfunc) override;

  /**
   * Subroutine to update new cluster centers from the old centers.
   * Called from within Learn (and will be overridden by vtkPKMeansStatistics
   * to handle distributed datasets).
   */
  virtual void UpdateClusterCenters(vtkTable* newClusterElements, vtkTable* curClusterElements,
    vtkIdTypeArray* numMembershipChanges, vtkIdTypeArray* numDataElementsInCluster,
    vtkDoubleArray* error, vtkIdTypeArray* startRunID, vtkIdTypeArray* endRunID,
    vtkIntArray* computeRun);

  /**
   * Subroutine to get the total number of observations.
   * Called from within Learn (and will be overridden by vtkPKMeansStatistics
   * to handle distributed datasets).
   */
  virtual vtkIdType GetTotalNumberOfObservations(vtkIdType numObservations);

  /**
   * Subroutine to initialize the cluster centers using those provided by the user
   * in input port LEARN_PARAMETERS.  If no cluster centers are provided, the subroutine uses the
   * first DefaultNumberOfClusters input data points as initial cluster centers.
   * Called from within Learn.
   */
  int InitializeDataAndClusterCenters(vtkTable* inParameters, vtkTable* inData,
    vtkTable* dataElements, vtkIdTypeArray* numberOfClusters, vtkTable* curClusterElements,
    vtkTable* newClusterElements, vtkIdTypeArray* startRunID, vtkIdTypeArray* endRunID);

  /**
   * Subroutine to initialize cluster centerss if not provided by the user.
   * Called from within Learn (and will be overridden by vtkPKMeansStatistics
   * to handle distributed datasets).
   */
  virtual void CreateInitialClusterCenters(vtkIdType numToAllocate,
    vtkIdTypeArray* numberOfClusters, vtkTable* inData, vtkTable* curClusterElements,
    vtkTable* newClusterElements);

  /**
   * This is the default number of clusters used when the user does not provide initial cluster
   * centers.
   */
  int DefaultNumberOfClusters;
  /**
   * This is the name of the column that specifies the number of clusters in each run.
   * This is only used if the user has not specified initial clusters.
   */
  char* KValuesArrayName;
  /**
   * This is the maximum number of iterations allowed if the new cluster centers have not yet
   * converged.
   */
  int MaxNumIterations;
  /**
   * This is the percentage of data elements that swap cluster IDs
   */
  double Tolerance;
  /**
   * This is the Distance functor.  The default is Euclidean distance, however this can be
   * overridden.
   */
  vtkKMeansDistanceFunctor* DistanceFunctor;

private:
  vtkKMeansStatistics(const vtkKMeansStatistics&) = delete;
  void operator=(const vtkKMeansStatistics&) = delete;
};

VTK_ABI_NAMESPACE_END
#endif
