code: def precompute_optimzation_Y(laplacian_matrix, n_samples, relaxation_kwds):
      
      relaxation_kwds.setdefault('presave',False)
      relaxation_kwds.setdefault('presave_name','pre_comp_current.npy')
      relaxation_kwds.setdefault('verbose',False)
      if relaxation_kwds['verbose']:
          print ('Making Lk and nbhds')
      Lk_tensor, nbk, si_map = \
          compute_Lk(laplacian_matrix, n_samples, relaxation_kwds['subset'])
      if relaxation_kwds['presave']:
          raise NotImplementedError('Not yet implemented presave')
      return { 'Lk': Lk_tensor, 'nbk': nbk, 'si_map': si_map }
docs: compute Lk, neighbors and subset to index map for projected == False