class_docstr: Online Updating Ensemble of forecasters.
  
  Parameters
  ----------
  ensemble_algorithm : ensemble algorithm
  forecasters : list of (str, estimator) tuples
  n_jobs : int or None, optional (default=None)
      The number of jobs to run in parallel for fit. None means 1 unless
      in a joblib.parallel_backend context.
      -1 means using all processors.
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docstr: Fit the ensemble.
  
  This makes predictions with individual forecasters and compares the
  results to actual values. This is then used to update ensemble
  weights.
  
  Parameters
  ----------
  y : pd.Series
      Target time series to which to fit the forecaster.
  X : pd.DataFrame, optional (default=None)
      Exogenous variables are ignored
docstr_tok: ["Fit","the","ensemble",".","This","makes","predictions","with","individual","forecasters","and","compares","the","results","to","actual","values",".","This","is","then","used","to","update","ensemble","weights",".","Parameters","--","--","--","--","--","y",":","pd.Series","Target","time","series","to","which","to","fit","the","forecaster",".","X",":","pd.DataFrame",",","optional","(","default=None",")","Exogenous","variables","are","ignored"]
code: def _fit_ensemble(self, y, X=None):
      """Fit the ensemble.
  
      This makes predictions with individual forecasters and compares the
      results to actual values. This is then used to update ensemble
      weights.
  
      Parameters
      ----------
      y : pd.Series
          Target time series to which to fit the forecaster.
      X : pd.DataFrame, optional (default=None)
          Exogenous variables are ignored
      """
      fh = np.arange(len(y)) + 1
      estimator_predictions = np.column_stack(
          self._predict_forecasters(fh, X)
      )
      y = np.array(y)
  
      self.ensemble_algorithm.update(estimator_predictions.T, y)
  
file_path: sktime/sktime/forecasting/online_learning/_online_ensemble.py
imports: import numpy
  import pandas
  from sktime.forecasting.compose._ensemble import EnsembleForecaster
label_desc: Use image node_id 3 for calling the OnlineEnsembleForecaster obj's underlying member method code with example usage: obj._fit_ensemble(y, X) without return types