old_contents: #!/usr/bin/env python
  import matplotlib.pyplot as plt
  
  from .constants import PLOT
  
  
  class ComparisonPlotter:
      def __init__(self, data_list):
          self.trajectory_fig, self.trajectory_plot = plt.subplots(1, 1)
          self.position_fig, self.position_plot = plt.subplots(2, 1, sharex=True)
          self.position_error_fig, self.position_error_plot = plt.subplots(2, 1, sharex=True)
          self.control_action_fig, self.control_action_plot = plt.subplots(2, 1, sharex=True)
  
          temp_data = data_list[0]
          self.t = temp_data['t']
          self.x_ref = temp_data['x_ref']
          self.y_ref = temp_data['y_ref']
          self.zeros = temp_data['zeros']
  
      def plot_comparison(self):
          self.trajectory_plot.plot(self.x_ref, self.y_ref, 'r--', label=r'${\rm reference}$', lw=PLOT['line_width'])
          plt.show()
  
  if __name__ == '__main__':
      steps = 100
      plotter = ComparisonPlotter(
          [
              {'t': [i for i in range(steps)],
               'x_ref': [0.5 * i for i in range(steps)],
               'y_ref': [2.0 * i for i in range(steps)],
               'zeros': [0.0 for _ in range(steps)],}
          ]
      )
      plotter.plot_comparison()
  
new_contents: #!/usr/bin/env python
  import matplotlib.pyplot as plt
  
  from .plotter import Plotter
  from .constants import PLOT
  
  
  class ComparisonPlotter(Plotter):
      def __init__(self, data_list):
          temp_data = data_list[0]
          Plotter.__init__(self, temp_data['t'], temp_data['zeros'])
  
          self.trajectory_fig, self.trajectory_plot = plt.subplots(1, 1)
          self.position_fig, self.position_plot = plt.subplots(2, 1, sharex=True)
          self.position_error_fig, self.position_error_plot = plt.subplots(2, 1, sharex=True)
          self.control_action_fig, self.control_action_plot = plt.subplots(2, 1, sharex=True)
  
          self.x_ref = temp_data['x_ref']
          self.y_ref = temp_data['y_ref']
  
      def plot_comparison(self):
          self.trajectory_plot.plot(self.x_ref, self.y_ref, 'r--', label=r'${\rm reference}$', lw=PLOT['line_width'])
          plt.show()
  
subject: Make class ComparisonPlotter inherit from Plotter