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api example code: fahrenheit_celsius_scales.pyΒΆ

(Source code, png, hires.png, pdf)

Show how to display two scales on the left and right y axis -- Fahrenheit and Celsius

import matplotlib.pyplot as plt

fig, ax1 = plt.subplots()  # ax1 is the Fahrenheit scale
ax2 = ax1.twinx()          # ax2 is 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))

# 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')

Keywords: python, matplotlib, pylab, example, codex (see Search examples)