class_docstr: Computes a kernel using the transportation distance as the distance. 
docstr: Returns the number of groups. 
docstr_tok: ["Returns","the","number","of","groups","."]
code: def _get_groups(cls, num_dists, num_dist_types):
      """Returns the number of groups."""
      num_dists_per_group = num_dists // num_dist_types
      groups = [
          [(i + num_dist_types * j) for j in range(num_dists_per_group)]
          for i in range(num_dist_types)
      ]
      return groups
  
imports: import numpy
  from .None import neural_network
  from ..gp.kernel import ExpSumOfDistsKernel, SumOfExpSumOfDistsKernel
  from ..utils.oper_utils import opt_transport
label_desc: Use image node_id 2 for calling the DistSumNNKernel obj's underlying member method code with example usage: obj._get_groups(cls, num_dists, num_dist_types) and returns: groups