docstr: This function returns only the average distance when calculating the
  distances between segmentation and reference
  
  :return:
docstr_tok: ["This","function","returns","only","the","average","distance","when","calculating","the","distances","between","segmentation","and","reference",":","return",":"]
code: def measured_average_distance(self):
      """
      This function returns only the average distance when calculating the
      distances between segmentation and reference
  
      :return:
      """
      return self.measured_distance()[1]
  
imports: from __future__ import absolute_import, print_function
  import numpy
  from scipy import ndimage
  from niftynet.utilities.util_common import MorphologyOps, CacheFunctionOutput
label_desc: Use image node_id 37 for calling the PairwiseMeasures obj's underlying member method code with example usage: obj.measured_average_distance() and returns: self