code: def get_deviations(self):
          
          bt = False
          if not self.istransformed:
              bt = True
              self._transform()
          mean_vec = self.mean()
  
          df = self.loc[:,:].copy()
          for col in df.columns:
              df.loc[:,col] -= mean_vec[col]
          if bt:
              self._back_transform()
          return type(self).from_dataframe(pst=self.pst,df=df)
docs: get the deviations of the ensemble value from the mean vector
  
          Returns
          -------
              en : pyemu.Ensemble
                  Ensemble of deviations from the mean