Plotting two variables on the same chart can be very useful to compare them against another variable.

Here is how to achieve this using Matplotlib.

# We import our libraries
import matplotlib.pyplot as plt
import numpy as np

# Generate our sample dataset
x = np.linspace(1,100)
y = np.sin(2 * np.pi * x)

# We create a canvas with one ax
fig, ax1 = plt.subplots(1, 1, figsize=(8,4))

# We plot on our first axis
ax1.plot(x, x, ls='--', alpha=0.6, c='tab:blue')

# We change the labels color of our first axis
ax1.tick_params('y', colors='tab:blue')

# We create our second ax based on our first ax
ax2 = ax1.twinx()
ax2.plot(x, y, ls='--', alpha=0.6, c='tab:red')

# We change the labels color of our second axis
ax2.tick_params('y', colors='tab:red')

# We tight the layout
fig.tight_layout()

# We plot
plt.show()

The result

Here you are! You now know how to plot two variables on the same plot with different y-axis scales.

More on Matplotlib

If you like what you've just read and want to know more about the Matplotlib library (e.g. how to add labels, plot different types of plots, etc...) check out the other articles I wrote on the topic, just here :

Matplotlib - The Python You Need

We gathered the only Python essentials that you will probably ever need.

The Python You Need