code: def mask_roi_unique(self):
          
          # There is no good inherent way in numpy to do this...
          # http://stackoverflow.com/q/16970982/
  
          # Also possible and simple:
          #return np.unique(zip(self.mask_1.mask_roi_sparse,self.mask_2.mask_roi_sparse))
  
          A = np.vstack([self.mask_1.mask_roi_sparse,self.mask_2.mask_roi_sparse]).T
          B = A[np.lexsort(A.T[::-1])]
          return B[np.concatenate(([True],np.any(B[1:]!=B[:-1],axis=1)))]
docs: Assemble a set of unique magnitude tuples for the ROI