mirror of
https://gitlab.kitware.com/vtk/vtk-m
synced 2024-09-08 21:33:55 +00:00
96 lines
3.1 KiB
C++
96 lines
3.1 KiB
C++
//============================================================================
|
|
// Copyright (c) Kitware, Inc.
|
|
// All rights reserved.
|
|
// See LICENSE.txt for details.
|
|
//
|
|
// This software is distributed WITHOUT ANY WARRANTY; without even
|
|
// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
|
|
// PURPOSE. See the above copyright notice for more information.
|
|
//============================================================================
|
|
|
|
#ifndef vtk_m_worklet_FieldEntropy_h
|
|
#define vtk_m_worklet_FieldEntropy_h
|
|
|
|
#include <vtkm/Math.h>
|
|
#include <vtkm/cont/Algorithm.h>
|
|
#include <vtkm/cont/ArrayHandle.h>
|
|
#include <vtkm/cont/ArrayHandleCounting.h>
|
|
#include <vtkm/worklet/DispatcherMapField.h>
|
|
#include <vtkm/worklet/FieldHistogram.h>
|
|
#include <vtkm/worklet/WorkletMapField.h>
|
|
|
|
#include <vtkm/cont/Field.h>
|
|
|
|
namespace vtkm
|
|
{
|
|
namespace worklet
|
|
{
|
|
|
|
//simple functor that returns basic statistics
|
|
class FieldEntropy
|
|
{
|
|
public:
|
|
// For each bin, calculate its information content (log2)
|
|
class SetBinInformationContent : public vtkm::worklet::WorkletMapField
|
|
{
|
|
public:
|
|
using ControlSignature = void(FieldIn freq, FieldOut informationContent);
|
|
using ExecutionSignature = void(_1, _2);
|
|
|
|
vtkm::Float64 FreqSum;
|
|
|
|
VTKM_CONT
|
|
SetBinInformationContent(vtkm::Float64 _freqSum)
|
|
: FreqSum(_freqSum)
|
|
{
|
|
}
|
|
|
|
template <typename FreqType>
|
|
VTKM_EXEC void operator()(const FreqType& freq, vtkm::Float64& informationContent) const
|
|
{
|
|
vtkm::Float64 p = ((vtkm::Float64)freq) / FreqSum;
|
|
if (p > 0)
|
|
informationContent = -1 * p * vtkm::Log2(p);
|
|
else
|
|
informationContent = 0;
|
|
}
|
|
};
|
|
|
|
|
|
// Execute the entropy computation filter given data(a field) and number of bins
|
|
// Returns:
|
|
// Entropy (log2) of the field of the data
|
|
template <typename FieldType, typename Storage>
|
|
vtkm::Float64 Run(vtkm::cont::ArrayHandle<FieldType, Storage> fieldArray, vtkm::Id numberOfBins)
|
|
{
|
|
///// calculate histogram using FieldHistogram worklet /////
|
|
vtkm::Range range;
|
|
FieldType delta;
|
|
vtkm::cont::ArrayHandle<vtkm::Id> binArray;
|
|
vtkm::worklet::FieldHistogram histogram;
|
|
histogram.Run(fieldArray, numberOfBins, range, delta, binArray);
|
|
|
|
///// calculate sum of frequency of the histogram /////
|
|
vtkm::Id initFreqSumValue = 0;
|
|
vtkm::Id freqSum = vtkm::cont::Algorithm::Reduce(binArray, initFreqSumValue, vtkm::Sum());
|
|
|
|
///// calculate information content of each bin using self-define worklet /////
|
|
vtkm::cont::ArrayHandle<vtkm::Float64> informationContent;
|
|
SetBinInformationContent binWorklet(static_cast<vtkm::Float64>(freqSum));
|
|
vtkm::worklet::DispatcherMapField<SetBinInformationContent> setBinInformationContentDispatcher(
|
|
binWorklet);
|
|
setBinInformationContentDispatcher.Invoke(binArray, informationContent);
|
|
|
|
///// calculate entropy by summing up information conetent of all bins /////
|
|
vtkm::Float64 initEntropyValue = 0;
|
|
vtkm::Float64 entropy =
|
|
vtkm::cont::Algorithm::Reduce(informationContent, initEntropyValue, vtkm::Sum());
|
|
|
|
return entropy;
|
|
}
|
|
};
|
|
}
|
|
} // namespace vtkm::worklet
|
|
|
|
#endif // vtk_m_worklet_FieldEntropy_h
|