docstr: Export rolling result in form of a tuple of numpy ndarray (x, y).
  
  :return: a 2-dim tuple. each item is a 3d numpy ndarray. The ndarray
           is casted to float32.
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code: def to_numpy(self):
      """
      Export rolling result in form of a tuple of numpy ndarray (x, y).
  
      :return: a 2-dim tuple. each item is a 3d numpy ndarray. The ndarray
               is casted to float32.
      """
      if self.numpy_x is None:
          raise RuntimeError(
              'Please call "roll" method\
                      before transform a TSDataset to numpy ndarray!'
          )
      return self.numpy_x, self.numpy_y
  
imports: import pandas
  import numpy
  import functools
  from zoo.chronos.data.utils.feature import generate_dt_features, generate_global_features
  from zoo.chronos.data.utils.impute import impute_timeseries_dataframe
  from zoo.chronos.data.utils.deduplicate import deduplicate_timeseries_dataframe
  from zoo.chronos.data.utils.roll import roll_timeseries_dataframe
  from zoo.chronos.data.utils.scale import unscale_timeseries_numpy
  from zoo.chronos.data.utils.resample import resample_timeseries_dataframe
  from zoo.chronos.data.utils.split import split_timeseries_dataframe
  from zoo.chronos.data.utils.utils import _to_list, _check_type, _check_col_within, _check_col_no_na, _check_is_aligned, _check_dt_is_sorted
  from tsfresh.utilities.dataframe_functions import roll_time_series
  from tsfresh.utilities.dataframe_functions import impute
  from tsfresh import extract_features
  from tsfresh.feature_extraction import ComprehensiveFCParameters, MinimalFCParameters, EfficientFCParameters
label_desc: Use image node_id 12 for calling the TSDataset obj's underlying member method code with example usage: obj.to_numpy() and returns: self,  self