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#ifndef vtkKMeansDistanceFunctor_h
#define vtkKMeansDistanceFunctor_h
/**
* @class vtkKMeansDistanceFunctor
* @brief measure distance from k-means cluster centers
*
* This is an abstract class (with a default concrete subclass) that implements
* algorithms used by the vtkKMeansStatistics filter that rely on a distance metric.
* If you wish to use a non-Euclidean distance metric (this could include
* working with strings that do not have a Euclidean distance metric, implementing
* k-mediods, or trying distance metrics in norms other than L2), you
* should subclass vtkKMeansDistanceFunctor.
*/
#include "vtkFiltersStatisticsModule.h" // For export macro
#include "vtkObject.h"
class vtkVariantArray;
class vtkAbstractArray;
class vtkTable;
class VTKFILTERSSTATISTICS_EXPORT vtkKMeansDistanceFunctor : public vtkObject
{
public:
static vtkKMeansDistanceFunctor* New();
vtkTypeMacro(vtkKMeansDistanceFunctor,vtkObject);
void PrintSelf( ostream& os, vtkIndent indent ) VTK_OVERRIDE;
/**
* Return an empty tuple. These values are used as cluster center coordinates
* when no initial cluster centers are specified.
*/
virtual vtkVariantArray* GetEmptyTuple( vtkIdType dimension );
/**
* Compute the distance from one observation to another, returning the distance
* in the first argument.
*/
virtual void operator() ( double&, vtkVariantArray*, vtkVariantArray * );
/**
* This is called once per observation per run per iteration in order to assign the
* observation to its nearest cluster center after the distance functor has been
* evaluated for all the cluster centers.
* The distance functor is responsible for incrementally updating the cluster centers
* to account for the assignment.
*/
virtual void PairwiseUpdate( vtkTable* clusterCenters, vtkIdType row, vtkVariantArray* data, vtkIdType dataCardinality, vtkIdType totalCardinality );
/**
* When a cluster center (1) has no observations that are closer to it than other cluster centers
* or (2) has exactly the same coordinates as another cluster center, its coordinates should be
* perturbed. This function should perform that perturbation.
* Since perturbation relies on a distance metric, this function is the responsibility of the
* distance functor.
*/
virtual void PerturbElement( vtkTable*, vtkTable*, vtkIdType, vtkIdType, vtkIdType, double );
/**
* Allocate an array large enough to hold \a size coordinates and return a void pointer to this array.
* This is used by vtkPKMeansStatistics to send (receive) cluster center coordinates to (from) other processes.
*/
virtual void* AllocateElementArray( vtkIdType size );
/**
* Free an array allocated with AllocateElementArray.
*/
virtual void DeallocateElementArray( void* );
/**
* Return a vtkAbstractArray capable of holding cluster center coordinates.
* This is used by vtkPKMeansStatistics to hold cluster center coordinates sent to (received from) other processes.
*/
virtual vtkAbstractArray* CreateCoordinateArray();
/**
* Pack the cluster center coordinates in \a vElements into columns of \a curTable.
* This code may assume that the columns in \a curTable are all of the type returned by \a GetNewVTKArray().
*/
virtual void PackElements( vtkTable* curTable, void* vElements );
//@{
/**
* Unpack the cluster center coordinates in \a vElements into columns of \a curTable.
* This code may assume that the columns in \a curTable are all of the type returned by \a GetNewVTKArray().
*/
virtual void UnPackElements( vtkTable* curTable, vtkTable* newTable, void* vLocalElements, void* vGlobalElements, int np );
virtual void UnPackElements( vtkTable* curTable, void* vLocalElements, vtkIdType numRows, vtkIdType numCols );
//@}
/**
* Return the data type used to store cluster center coordinates.
*/
virtual int GetDataType();
protected:
vtkKMeansDistanceFunctor();
~vtkKMeansDistanceFunctor() VTK_OVERRIDE;
vtkVariantArray* EmptyTuple; // Used to quickly initialize Tuple for each datum
vtkTable* CenterUpdates; // Used to hold online computation of next iteration's cluster center coords.
private:
vtkKMeansDistanceFunctor( const vtkKMeansDistanceFunctor& ) VTK_DELETE_FUNCTION;
void operator = ( const vtkKMeansDistanceFunctor& ) VTK_DELETE_FUNCTION;
};
#endif // vtkKMeansDistanceFunctor_h
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