class_docstr: Base class for forecasters that use sliding windows.
class_docstr_tok: ["Base","class","for","forecasters","that","use","sliding","windows","."]
docstr: Create a return DataFrame for predict-like method, with all np.nan entries.
  
  Parameters
  ----------
  fh : ForecastingHorizon of self, optional (default=None)
      retrieved from self.fh if None
  method : str, optional (default="predict")
      method name to generate return DataFrame for
      name of one of the BaseForecaster predict-like methods
  **kwargs : optional
      further kwargs to predict-like methods, e.g., coverage for predict_interval
      passed to self._get_columns
  
  Returns
  -------
  y_pred : pd.DataFrame
      return DataFrame
      index, columns are as expected
      all entries are np.nan
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code: def _predict_nan(self, fh=None, method="predict", **kwargs):
      """Create a return DataFrame for predict-like method, with all np.nan entries.
  
      Parameters
      ----------
      fh : ForecastingHorizon of self, optional (default=None)
          retrieved from self.fh if None
      method : str, optional (default="predict")
          method name to generate return DataFrame for
          name of one of the BaseForecaster predict-like methods
      **kwargs : optional
          further kwargs to predict-like methods, e.g., coverage for predict_interval
          passed to self._get_columns
  
      Returns
      -------
      y_pred : pd.DataFrame
          return DataFrame
          index, columns are as expected
          all entries are np.nan
      """
      if fh is None:
          fh = self.fh
  
      index = fh.get_expected_pred_idx(y=self._y, cutoff=self.cutoff)
      columns = self._get_columns(method=method, **kwargs)
  
      y_pred = pd.DataFrame(np.nan, index=index, columns=columns)
      return y_pred
  
file_path: sktime/sktime/forecasting/base/_sktime.py
imports: import numpy
  import pandas
  from sktime.forecasting.base._base import BaseForecaster
  from sktime.split import CutoffSplitter
  from sktime.utils.datetime import _shift
label_desc: Use image node_id 8 for calling the _BaseWindowForecaster obj's underlying member method code with example usage: obj._predict_nan(fh, method) and returns: y_pred