class_docstr: Minimal interface for a NiftyNet evaluation
docstr: Returns aggregations to compute for the metric. Each aggregation is
  a callable that computes a list of DataFrames from a dictionary of 
  metric dataframes (index by the DataFrame index). See
  BaseEvaluator.ScalarAggregator for an example.
  
  :return: list of aggregation callables
code: def get_aggregations(self):
      """
      Returns aggregations to compute for the metric. Each aggregation is
      a callable that computes a list of DataFrames from a dictionary of
      metric dataframes (index by the DataFrame index). See
      BaseEvaluator.ScalarAggregator for an example.
  
      :return: list of aggregation callables
      """
      return []
  
file_path: NiftyNet/niftynet/evaluation/base_evaluations.py
imports: from __future__ import absolute_import, division, print_function
  import pandas
  from niftynet.layer.base_layer import Layer
label_desc: Use image node_id 2 for calling the BaseEvaluation obj's underlying member method code with example usage: obj.get_aggregations() and returns: list