Method Initialize

Filters/General/vtkTableFFT.cxx:209–262

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
void vtkTableFFT::Initialize(vtkTable* input)
{
  // Find time array and compute sample rate
  const std::size_t nsamples = input->GetNumberOfRows();
  vtkDataArray* timeArray = nullptr;
  bool complexColumnFound = false;
  for (vtkIdType col = 0; col < input->GetNumberOfColumns(); col++)
  {
    vtkAbstractArray* column = input->GetColumn(col);

    if (vtksys::SystemTools::Strucmp(column->GetName(), "time") == 0)
    {
      timeArray = vtkDataArray::SafeDownCast(input->GetColumn(col));
    }

    complexColumnFound |= (column->GetNumberOfComponents() == 2);
  }

  if (this->ReturnOnesided && complexColumnFound)
  {
    vtkWarningMacro("ReturnOnesided is True but found columns with 2 components"
                    " (interpreted as imaginary data). Imaginary columns will be ignored.");
  }

  if (timeArray && timeArray->GetNumberOfTuples() > 1)
  {
    double deltaT = timeArray->GetTuple1(1) - timeArray->GetTuple1(0);
    this->Internals->SampleRate = 1.0 / deltaT;
  }
  else
  {
    this->Internals->SampleRate = this->DefaultSampleRate;
  }

  // Check if we can average and compute the size of the windowing function
  std::size_t nfft = nsamples;
  if (this->AverageFft)
  {
    nfft = std::min(static_cast<std::size_t>(this->BlockSize), nsamples);
  }

  // Generate windowing function
  // We're caching the windowing function for more efficiency when applying this filter
  // on different tables multiple times
  if (this->Internals->WindowLastUpdated < this->Internals->WindowTimeStamp.GetMTime() ||
    nfft != this->Internals->Window.size())
  {
    this->Internals->UpdateWindow(this->WindowingFunction, nfft);
    this->Internals->WindowLastUpdated = this->Internals->WindowTimeStamp.GetMTime();
  }

  // Get output size
  this->Internals->OutputSize = this->ReturnOnesided ? (nfft / 2) + 1 : nfft;
}

//------------------------------------------------------------------------------
vtkSmartPointer<vtkDataArray> vtkTableFFT::DoFFT(vtkDataArray* input)