Method GenerateSubset

Filters/ParallelStatistics/vtkGenerateStatistics.cxx:1359–1411

}

void vtkGenerateStatistics::GenerateSubset(std::unordered_map<vtkIdType, vtkIdType>& subset,
  vtkIdType numberOfSamples, double trainingFraction, vtkUnsignedCharArray* ghostData,
  unsigned char ghostMask)
{
  if (!ghostData)
  {
    vtkReservoirSampler<vtkIdType, /* monotonic output */ false> sampler;
    std::vector<vtkIdType> ids = sampler(numberOfSamples * trainingFraction, numberOfSamples);
    vtkIdType out = 0;
    for (const auto& id : ids)
    {
      subset[id] = out;
      ++out;
    }
  }
  else
  {
    vtkIdType actualNumberOfSamples = 0;
    // Count non-ghost values:
    for (vtkIdType ii = 0; ii < ghostData->GetNumberOfValues(); ++ii)
    {
      if ((ghostData->GetValue(ii) & ghostMask) == 0)
      {
        ++actualNumberOfSamples;
      }
    }
    // Compute indices as if ghost values were not present:
    vtkReservoirSampler<vtkIdType, /* monotonic output */ true> sampler;
    std::vector<vtkIdType> ids =
      sampler(actualNumberOfSamples * trainingFraction, actualNumberOfSamples);
    // Compute actual sample indices by skipping ghosts:
    vtkIdType virtualIndex = 0;
    auto idIt = ids.begin();
    vtkIdType out = 0;
    for (vtkIdType ii = 0; ii < ghostData->GetNumberOfValues(); ++ii)
    {
      if ((ghostData->GetValue(ii) & ghostMask) == 0)
      {
        if (*idIt == virtualIndex)
        {
          subset[ii] = out++;
          ++idIt;
          if (idIt == ids.end())
          {
            // Terminate early; we have all our samples.
            break;
          }
        }
        ++virtualIndex;
      }
    }
  }
}

void vtkGenerateStatistics::ComputeCellToPointWeights(
  PointsOfCellsWeightMap& cellsToPointsToWeights, vtkDataSet* dataSet,