code: def _summarize_in_roi(self, label_mask, num_clusters_per_roi=1, metric='minkowski'):
          
  
          this_label = self.carpet[label_mask.flatten(), :]
          if num_clusters_per_roi == 1:
              out_matrix = self._summary_func(this_label, axis=0)
          else:
              out_matrix = self._make_clusters(this_label, num_clusters_per_roi, metric)
  
          return out_matrix
docs: returns a single row summarizing (typically via mean) all rows in an ROI.