code: def __init__(self, test=None, reference=None):
      self.tp = None
      self.fp = None
      self.tn = None
      self.fn = None
      self.size = None
      self.reference_empty = None
      self.reference_full = None
      self.test_empty = None
      self.test_full = None
      self.set_reference(reference)
      self.set_test(test)
  
imports: import numpy
  from medpy import metric
label_desc: Use image node_id 1 to create a new ConfusionMatrix object  with example: obj = ConfusionMatrix(test, reference)