matplotlib-python two subplots on the same canvas

The most basic module in Matplotlib is pyplot. The idiomatic aliases for matplotlib and matplotlib.pyplot are mpl and plt, respectively.

import matplotlib as mpl
import matplotlib.pyplot as plt

In Matplotlib, there are two common concepts when drawing a picture. One is the window that pops up when drawing pictures, called figure. The figure is equivalent to a large canvas. In each figure, there can be multiple sub-figures. Such sub-figures are called axes. As the name suggests, with the horizontal and vertical axis is a simple chart.
In the following code, first define the figure as a large canvas with 1 row and 2 columns, and then add two new subplots through "fig.add_subplot()". The definition format of subplot is very interesting. The first two digits of the number define the number of rows and columns respectively, and the last digit defines the order of the newly added subplot.

import numpy as np
import matplotlib.pyplot as plt

mpl.rcParams['axes.titlesize'] = 10  #子图的标题大小
mpl.rcParams['axes.labelsize'] = 10  #子图的标签大小
mpl.rcParams['xtick.labelsize'] = 8  #横轴字体大小
mpl.rcParams['ytick.labelsize'] = 8  #纵轴字体大小
mpl.rcParams['xtick.major.size'] = 0  #x轴最大刻度大小
mpl.rcParams['ytick.major.size'] = 0  #y轴最大刻度大小

fig = plt.figure('Bar chart & Pie chart')  #整体图的标题
speed_map = {
    
    
    'dog': (48, '#7199cf'),
    'cat': (45, '#4fc4aa'),
    'cheetah': (120, '#e1a7a2')
}

#①在121位置上添加柱图，通过fig.add_subplot()加入子图
ax = fig.add_subplot(121)  
ax.set_title('Running speed - bar chart')  #子图标题
xticks = np.arange(3)  #生成x轴每个元素的位置
speeds = [x[0] for x in speed_map.values()]  #奔跑速度
bar_width = 0.5  #定义柱状图每个柱的宽度

#设置x、y轴的范围
ax.set_xlim([bar_width/2-1, 3-bar_width/2])
ax.set_ylim([0, 125])
#设置x轴标签
animals = speed_map.keys()  
ax.set_xticklabels(animals) 
ax.set_xticks(xticks)  #设置x轴上每个标签的具体位置
#设置y轴的标签
ax.set_ylabel('Speed(km/h)')  

bars = ax.bar(xticks, speeds, width=bar_width, edgecolor='none')  #设置柱的边缘为透明
colors = [x[1] for x in speed_map.values()]  #对应颜色
for bar, color in zip(bars, colors):  #给每个bar分配指定的颜色
    bar.set_color(color)
    
    
#②在122位置加入饼图
ax = fig.add_subplot(122)
ax.set_title('Running speed - pie chart')
# 生成同时包含名称和速度的标签
labels = ['{}\n{} km/h'.format(animal, speed) for animal, speed in zip(animals, speeds)]
# 画饼状图，并指定标签和对应颜色
ax.pie(speeds, labels=labels, colors=colors)
ax.axis('equal')   #保证饼图不变形
 
    
plt.savefig('Bar chart & Pie chart.png')  #保存为图片
plt.show()