code: def get_thresholdcurve_data(data, xname, yname):
      
      xi = data.attribute_by_name(xname).index
      yi = data.attribute_by_name(yname).index
      x = []
      y = []
      for i in range(data.num_instances):
          inst = data.get_instance(i)
          x.append(inst.get_value(xi))
          y.append(inst.get_value(yi))
      return x, y
docs: Retrieves x and y columns from  of the data generated by the weka.classifiers.evaluation.ThresholdCurve
      class.
  
      :param data: the threshold curve data
      :type data: Instances
      :param xname: the name of the X column
      :type xname: str
      :param yname: the name of the Y column
      :type yname: str
      :return: tuple of x and y arrays
      :rtype: tuple