mirror of
https://gitlab.kitware.com/vtk/vtk-m
synced 2024-09-19 18:45:43 +00:00
108 lines
3.8 KiB
C++
108 lines
3.8 KiB
C++
//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//
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// Copyright 2014 Sandia Corporation.
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// Copyright 2014 UT-Battelle, LLC.
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// Copyright 2014 Los Alamos National Security.
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//
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// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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// the U.S. Government retains certain rights in this software.
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//
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// Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
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// Laboratory (LANL), the U.S. Government retains certain rights in
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// this software.
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//============================================================================
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#ifndef vtk_m_worklet_FieldEntropy_h
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#define vtk_m_worklet_FieldEntropy_h
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#include <vtkm/Math.h>
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#include <vtkm/cont/ArrayHandle.h>
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#include <vtkm/cont/ArrayHandleCounting.h>
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#include <vtkm/worklet/DispatcherMapField.h>
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#include <vtkm/worklet/WorkletMapField.h>
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#include <vtkm/cont/DeviceAdapter.h>
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#include <vtkm/worklet/FieldHistogram.h>
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#include <vtkm/cont/Field.h>
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typedef VTKM_DEFAULT_DEVICE_ADAPTER_TAG DeviceAdapter;
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namespace vtkm {
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namespace worklet {
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//simple functor that returns basic statistics
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class FieldEntropy
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{
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public:
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// For each bin, calculate its information content (log2)
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class SetBinInformationContent : public vtkm::worklet::WorkletMapField
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{
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public:
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typedef void ControlSignature(FieldIn<> freq,
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FieldOut<> informationContent);
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typedef void ExecutionSignature(_1,_2);
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vtkm::Float64 FreqSum;
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VTKM_CONT
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SetBinInformationContent(vtkm::Float64 _freqSum) : FreqSum(_freqSum) {}
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template<typename FreqType>
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VTKM_EXEC
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void operator()(const FreqType &freq, vtkm::Float64 &informationContent) const
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{
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vtkm::Float64 p = ( (vtkm::Float64)freq ) / FreqSum;
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if( p > 0 )
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informationContent = -1 * p * vtkm::Log2(p);
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else
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informationContent = 0;
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}
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};
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// Execute the entropy computation filter given data(a field) and number of bins
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// Returns:
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// Entropy (log2) of the field of the data
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template<typename FieldType, typename Storage, typename DeviceAdapter>
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vtkm::Float64 Run(vtkm::cont::ArrayHandle<FieldType, Storage> fieldArray,
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vtkm::Id numberOfBins,
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DeviceAdapter device)
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{
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typedef typename vtkm::cont::DeviceAdapterAlgorithm<DeviceAdapter> DeviceAlgorithms;
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///// calculate histogram using FieldHistogram worklet /////
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vtkm::Range range;
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FieldType delta;
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vtkm::cont::ArrayHandle<vtkm::Id> binArray;
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vtkm::worklet::FieldHistogram histogram;
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histogram.Run(fieldArray, numberOfBins, range, delta, binArray, device);
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///// calculate sum of frequency of the histogram /////
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vtkm::Id initFreqSumValue = 0;
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vtkm::Id freqSum = DeviceAlgorithms::Reduce(binArray, initFreqSumValue, vtkm::Sum());
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///// calculate information content of each bin using self-define worklet /////
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vtkm::cont::ArrayHandle<vtkm::Float64> informationContent;
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SetBinInformationContent binWorklet( static_cast<vtkm::Float64> (freqSum) );
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vtkm::worklet::DispatcherMapField< SetBinInformationContent > setBinInformationContentDispatcher(binWorklet);
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setBinInformationContentDispatcher.Invoke(binArray, informationContent);
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///// calculate entropy by summing up information conetent of all bins /////
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vtkm::Float64 initEntropyValue = 0;
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vtkm::Float64 entropy = DeviceAlgorithms::Reduce(informationContent, initEntropyValue, vtkm::Sum());
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return entropy;
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}
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};
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}
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} // namespace vtkm::worklet
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#endif // vtk_m_worklet_FieldHistogram_h
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