150 lines
6.0 KiB
C++
150 lines
6.0 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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//
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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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#ifndef vtk_m_worklet_AverageByKey_h
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#define vtk_m_worklet_AverageByKey_h
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#include <vtkm/VecTraits.h>
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#include <vtkm/cont/ArrayCopy.h>
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#include <vtkm/cont/ArrayHandle.h>
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#include <vtkm/worklet/DescriptiveStatistics.h>
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#include <vtkm/worklet/Keys.h>
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#include <vtkm/worklet/WorkletReduceByKey.h>
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namespace vtkm
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{
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namespace worklet
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{
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struct AverageByKey
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{
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struct AverageWorklet : public vtkm::worklet::WorkletReduceByKey
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{
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using ControlSignature = void(KeysIn keys, ValuesIn valuesIn, ReducedValuesOut averages);
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using ExecutionSignature = _3(_2);
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using InputDomain = _1;
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template <typename ValuesVecType>
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VTKM_EXEC typename ValuesVecType::ComponentType operator()(const ValuesVecType& valuesIn) const
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{
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using FieldType = typename ValuesVecType::ComponentType;
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FieldType sum = valuesIn[0];
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for (vtkm::IdComponent index = 1; index < valuesIn.GetNumberOfComponents(); ++index)
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{
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FieldType component = valuesIn[index];
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// FieldType constructor is for when OutType is a Vec.
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// static_cast is for when FieldType is a small int that gets promoted to int32.
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sum = static_cast<FieldType>(sum + component);
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}
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// To get the average, we (of course) divide the sum by the amount of values, which is
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// returned from valuesIn.GetNumberOfComponents(). To do this, we need to cast the number of
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// components (returned as a vtkm::IdComponent) to a FieldType. This is a little more complex
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// than it first seems because FieldType might be a Vec type. If you just try a
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// static_cast<FieldType>(), it will use the constructor to FieldType which might be a Vec
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// constructor expecting the type of the component. So, get around this problem by first
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// casting to the component type of the field and then constructing a field value from that.
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// We use the VecTraits class to make this work regardless of whether FieldType is a real Vec
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// or just a scalar.
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using ComponentType = typename vtkm::VecTraits<FieldType>::ComponentType;
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// FieldType constructor is for when OutType is a Vec.
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// static_cast is for when FieldType is a small int that gets promoted to int32.
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return static_cast<FieldType>(
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sum / FieldType(static_cast<ComponentType>(valuesIn.GetNumberOfComponents())));
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}
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};
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/// \brief Compute average values based on a set of Keys.
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///
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/// This method uses an existing \c Keys object to collected values by those keys and find
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/// the average of those groups.
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///
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template <typename InArrayType, typename OutArrayType>
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VTKM_CONT static void Run(const vtkm::worklet::internal::KeysBase& keys,
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const InArrayType& inValues,
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OutArrayType& outAverages)
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{
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vtkm::worklet::DispatcherReduceByKey<AverageWorklet> dispatcher;
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dispatcher.Invoke(keys, inValues, outAverages);
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}
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/// \brief Compute average values based on a set of Keys.
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///
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/// This method uses an existing \c Keys object to collected values by those keys and find
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/// the average of those groups.
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///
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template <typename ValueType, typename InValuesStorage>
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VTKM_CONT static vtkm::cont::ArrayHandle<ValueType> Run(
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const vtkm::worklet::internal::KeysBase& keys,
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const vtkm::cont::ArrayHandle<ValueType, InValuesStorage>& inValues)
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{
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vtkm::cont::ArrayHandle<ValueType> outAverages;
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Run(keys, inValues, outAverages);
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return outAverages;
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}
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struct ExtractKey
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{
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template <typename First, typename Second>
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VTKM_EXEC First operator()(const vtkm::Pair<First, Second>& pair) const
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{
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return pair.first;
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}
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};
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struct ExtractMean
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{
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template <typename KeyType, typename ValueType>
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VTKM_EXEC ValueType operator()(
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const vtkm::Pair<KeyType, vtkm::worklet::DescriptiveStatistics::StatState<ValueType>>& pair)
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const
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{
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return pair.second.Mean();
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}
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};
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/// \brief Compute average values based on an array of keys.
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///
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/// This method uses an array of keys and an equally sized array of values. The keys in that
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/// array are collected into groups of equal keys, and the values corresponding to those groups
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/// are averaged.
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///
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/// This method is less sensitive to constructing large groups with the keys than doing the
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/// similar reduction with a \c Keys object. For example, if you have only one key, the reduction
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/// will still be parallel. However, if you need to run the average of different values with the
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/// same keys, you will have many duplicated operations.
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///
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template <class KeyType,
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class ValueType,
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class KeyInStorage,
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class KeyOutStorage,
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class ValueInStorage,
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class ValueOutStorage>
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VTKM_CONT static void Run(const vtkm::cont::ArrayHandle<KeyType, KeyInStorage>& keyArray,
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const vtkm::cont::ArrayHandle<ValueType, ValueInStorage>& valueArray,
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vtkm::cont::ArrayHandle<KeyType, KeyOutStorage>& outputKeyArray,
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vtkm::cont::ArrayHandle<ValueType, ValueOutStorage>& outputValueArray)
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{
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auto results = vtkm::worklet::DescriptiveStatistics::Run(keyArray, valueArray);
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// Copy/TransformCopy from results to outputKeyArray and outputValueArray
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auto results_key = vtkm::cont::make_ArrayHandleTransform(results, ExtractKey{});
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auto results_mean = vtkm::cont::make_ArrayHandleTransform(results, ExtractMean{});
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vtkm::cont::ArrayCopy(results_key, outputKeyArray);
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vtkm::cont::ArrayCopy(results_mean, outputValueArray);
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}
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};
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}
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} // vtkm::worklet
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#endif //vtk_m_worklet_AverageByKey_h
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