.. _api-fahrenheit_celsius_scales:

api example code: fahrenheit_celsius_scales.py
==============================================



.. plot:: /home/mdboom/Work/builds/matplotlib/doc/mpl_examples/api/fahrenheit_celsius_scales.py

::

    """
    Show how to display two scales on the left and right y axis -- Fahrenheit and Celsius
    """
    
    import matplotlib.pyplot as plt
    
    fig = plt.figure()
    ax1 = fig.add_subplot(111)     # the Fahrenheit scale
    ax2 = ax1.twinx()              # the Celsius scale
    
    def Tc(Tf):
        return (5./9.)*(Tf-32)
    
    
    def update_ax2(ax1):
       y1, y2 = ax1.get_ylim()
       ax2.set_ylim(Tc(y1), Tc(y2))
       ax2.figure.canvas.draw()
    
    # automatically update ylim of ax2 when ylim of ax1 changes.
    ax1.callbacks.connect("ylim_changed", update_ax2)
    ax1.plot([78, 79, 79, 77])
    
    ax1.set_title('Two scales: Fahrenheit and Celsius')
    ax1.set_ylabel('Fahrenheit')
    ax2.set_ylabel('Celsius')
    
    plt.show()
    

Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)