code: def _create_labels_for_features(self, X):
          
          if self.labels is None:
              # Use column names if a dataframe
              if is_dataframe(X):
                  self.features_ = np.array(X.columns)
              # Otherwise use the column index as the labels
              else:
                  _, ncols = X.shape
                  self.features_ = np.arange(0, ncols)
          else:
              self.features_ = np.array(self.labels)
docs: Create labels for the features
  
          NOTE: this code is duplicated from MultiFeatureVisualizer