docstr: This function the intersection over union ratio - Definition of
  jaccard coefficient
  
  :return:
docstr_tok: ["This","function","the","intersection","over","union","ratio","-","Definition","of","jaccard","coefficient",":","return",":"]
code: def intersection_over_union(self):
      """
      This function the intersection over union ratio - Definition of
      jaccard coefficient
  
      :return:
      """
      return self.n_intersection() / self.n_union()
  
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 26 for calling the PairwiseMeasures obj's underlying member method code with example usage: obj.intersection_over_union() and returns: unknown