class_docstr: An internal class to manage filters/algorithms for uniform grid datasets.
class_docstr_tok: ["An","internal","class","to","manage","filters\/algorithms","for","uniform","grid","datasets","."]
docstr: Check for complex active scalars.
  
  This is necessary for rfft, low_pass, and high_pass filters.
docstr_tok: ["Check","for","complex","active","scalars",".","This","is","necessary","for","rfft",",","low_pass",",","and","high_pass","filters","."]
code: def _check_fft_scalars(self):
      """Check for complex active scalars.
  
      This is necessary for rfft, low_pass, and high_pass filters.
  
      """
      # check for complex active point scalars, otherwise the risk of segfault
      if self.point_data.active_scalars_name is None:
          possible_scalars = self.point_data.keys()
          if len(possible_scalars) == 1:
              self.set_active_scalars(
                  possible_scalars[0], preference="point"
              )
          elif len(possible_scalars) > 1:
              raise AmbiguousDataError(
                  "There are multiple point scalars available. Set one to be "
                  "active with `point_data.active_scalars_name = `"
              )
          else:
              raise MissingDataError(
                  "FFT filters require point scalars."
              )
  
      if not np.issubdtype(
          self.point_data.active_scalars.dtype, np.complexfloating
      ):
          raise ValueError(
              "Active scalars must be complex data for this filter, represented "
              "as an array with a datatype of `numpy.complex64` or "
              "`numpy.complex128`."
          )
  
imports: import collections.abc
  from typing import Literal, Optional, cast
  import numpy
  import pyvista
  from pyvista.core import _vtk_core
  from pyvista.core.errors import AmbiguousDataError, MissingDataError
  from pyvista.core.filters import _get_output, _update_alg
  from pyvista.core.filters.data_set import DataSetFilters
  from pyvista.core.utilities.arrays import FieldAssociation, set_default_active_scalars
  from pyvista.core.utilities.helpers import wrap
  from pyvista.core.utilities.misc import abstract_class
label_desc: Use image node_id 11 for calling the ImageDataFilters obj's underlying member method code with example usage: obj._check_fft_scalars() without return types