>>> """
=================================
Different scales on the same axes
=================================

Demo of how to display two scales on the left and right y axis.

This example uses the Fahrenheit and Celsius scales.
"""
... import matplotlib.pyplot as plt
... import numpy as np
... 
... 
... def fahrenheit2celsius(temp):
...     """
    Returns temperature in Celsius given Fahrenheit temperature.
    """
...     return (5. / 9.) * (temp - 32)
... 
... 
... def make_plot():
... 
...     # Define a closure function to register as a callback
...     def convert_ax_c_to_celsius(ax_f):
...         """
        Update second axis according with first axis.
        """
...         y1, y2 = ax_f.get_ylim()
...         ax_c.set_ylim(fahrenheit2celsius(y1), fahrenheit2celsius(y2))
...         ax_c.figure.canvas.draw()
... 
...     fig, ax_f = plt.subplots()
...     ax_c = ax_f.twinx()
... 
...     # automatically update ylim of ax2 when ylim of ax1 changes.
...     ax_f.callbacks.connect("ylim_changed", convert_ax_c_to_celsius)
...     ax_f.plot(np.linspace(-40, 120, 100))
...     ax_f.set_xlim(0, 100)
... 
...     ax_f.set_title('Two scales: Fahrenheit and Celsius')
...     ax_f.set_ylabel('Fahrenheit')
...     ax_c.set_ylabel('Celsius')
... 
...     plt.show()
... 
... make_plot()
...