This article will show you how to add the second y-axis with a label on Matplotlib plots.
1. How To Add The Second Y-Axis Label On Matplotlib Plot.
- First plot the first curve with the default x, y-axis.
# plot the first curve. plt.plot(x,y1)
- Then call the matplotlib.pyplot module’s twinx() method to add the second y-axis on the figure right side.
# add another y-axis. plt.twinx()
- Now you can plot the second curve, and the second curve will use the same x-axis and the second y-axis.
# plot the second curve, the curve line has green color. plt.plot(x,y2,'g')
2. Add The Second Y-Axis On Matplotlib Plot Example.
- Below is the example full source code.
import numpy as np import matplotlib.pyplot as plt def second_y_axis_example(): # create a numpy array contains integer number 1 - 10.. x=np.arange(1,10) print('x: ', x) # calculate y1. y1 = x + x print('y1: ', y1) # calculate y2. y2 = np.log(x) print('y2: ', y2) # plot the first curve. plt.plot(x,y1) # set the matplotlib plot title. plt.title('matplotlib add second y-axis example') # add another y-axis. plt.twinx() # plot the second curve, the curve line has green color. plt.plot(x,y2,'g') # display the plot. plt.show() if __name__ == '__main__': second_y_axis_example()
- When you run the above example, you can get the below figure.