Method Sort

Common/DataModel/vtkSortFieldData.cxx:25–88

------------------------------------------------------------------------------ Using vtkSortDataArray, it's easy to loop over all of the arrays in the field data and sort them. Initially we just need to generate the sort indices which are then applied to each array in turn.

// field data and sort them. Initially we just need to generate the sort
// indices which are then applied to each array in turn.
vtkIdType* vtkSortFieldData::Sort(
  vtkFieldData* fd, const char* arrayName, int k, int retIndices, int dir)
{
  // Verify the input
  if (fd == nullptr || arrayName == nullptr)
  {
    vtkGenericWarningMacro("SortFieldData needs valid input");
    return nullptr;
  }
  int pos;
  vtkAbstractArray* array = fd->GetAbstractArray(arrayName, pos);
  if (pos < 0)
  {
    vtkGenericWarningMacro("Sorting array not found.");
    return nullptr;
  }
  int numComp = array->GetNumberOfComponents();
  if (k < 0 || k >= numComp)
  {
    vtkGenericWarningMacro("Cannot sort by column "
      << k << " since the array only has columns 0 through " << (numComp - 1));
    return nullptr;
  }
  vtkIdType numKeys = array->GetNumberOfTuples();
  if (numKeys <= 0)
  {
    return nullptr;
  }

  // Create and initialize the sorting indices
  vtkIdType* idx = vtkSortDataArray::InitializeSortIndices(numKeys);

  // Sort and generate the sorting indices
  void* dataIn = array->GetVoidPointer(0);
  int dataType = array->GetDataType();
  vtkSortDataArray::GenerateSortIndices(dataType, dataIn, numKeys, numComp, k, idx);

  // Now loop over all arrays in the field data. Those that are the
  // same length as the sorting indices are processed. Otherwise they
  // are skipped and remain unchanged.
  int nc, numArrays = fd->GetNumberOfArrays();
  for (int arrayNum = 0; arrayNum < numArrays; ++arrayNum)
  {
    array = fd->GetAbstractArray(arrayNum);
    if (array != nullptr && array->GetNumberOfTuples() == numKeys)
    { // process the array
      dataIn = array->GetVoidPointer(0);
      dataType = array->GetDataType();
      nc = array->GetNumberOfComponents();
      vtkSortDataArray::ShuffleArray(idx, dataType, numKeys, nc, array, dataIn, dir);
    }
  }

  // Clean up
  if (retIndices)
  {
    return idx;
  }