Matplotlib Tutorial

Matplotlib Dual Axes

It is sometimes useful to have dual x or y axes in a graph. Moreover, when plotting curves with different units. Matplotlib supports this feature through the twinx() and twiny() functions.

In the following example, the plot has dual y-axes, one showing exp(x), and the other showing log(x) -

Example

# Filename : example.py
# Copyright :　2020 By w3codebox
# Author by : www.oldtoolbag.com
# Date :　2020-08-08
#!　/usr/bin/env python
　#coding=utf-8
　import matplotlib.pyplot as plt
　import numpy as np
　import math
　plt.rcParams['font.sans-serif'] = ['SimHei']  # Step one (replacement of sans-serif font)
　plt.rcParams['axes.unicode_minus'] = False  # Original source from 【Lidihuo】, commercial redistribution please contact the author for authorization, non-commercial please retain the original link:
　fig = plt.figure()
　a1　= fig.add_axes([0,0,1,1])
　x = np.arange(1,11)
　a1.plot(x, np.exp(x))
　a1.set_ylabel('exp')
　a2　= a1.twinx()
　a2.plot(x, np.log(x),'ro-')
　a2.set_ylabel('log')
　fig.legend(labels=('exp','log'),loc='upper left')
　plt.show()

Execute the above example code to get the following result -

Matplotlib Bar Chart Matplotlib Scales