students['2017'].sort_values(ascending=True).plot.pie(fontsize=6,startangle=-270)

可以用在乱序的情况

任务12：绘制饼图

绘制饼图是针对一个seriers

students['2017'].plot.pie(fontsize=8, counterclock=False)

注：counterclock=False：顺时针排列

本节代码：

import pandas as pd
import matplotlib.pyplot as plt

students = pd.read_excel('C:/Temp/Students.xlsx', index_col='From')
print(students)

students['2017'].plot.pie(fontsize=8, counterclock=False)
plt.title('Source of International Students', fontsize=16, fontweight='bold')
plt.ylabel('2017', fontsize=12, fontweight='bold')
plt.show()

打印结果：

                Rank    2016    2017
From                                
China              1  328547  350755
India              2  165918  186267
South Korea        3   61007   58663
Saudi Arabia       4   61287   52611
Canada             5   26973   27065
Vietnam            6   21403   22438
Taiwan             7   21127   21516
Japan              8   19060   18780
Mexico             9   16733   16835
Brazil            10   19370   13089
Iran              11   12269   12643
Nigeria           12   10674   11710
Nepal             13    9662   11607
United Kingdom    14   11599   11489
Turkey            15   10691   10586
Germany           16   10145   10169
Kuwait            17    9772    9825
France            18    8764    8814
Indonesia         19    8727    8776
Venezuela         20    8267    8540
Malaysia          21    7834    8247
Colombia          22    7815    7982
Hong Kong         23    7923    7547
Spain             24    6640    7164
Bangladesh        25    6513    7143

任务12：绘制饼图时，需要加上：plt.axis('equal')，确保饼图是一个正圆，否则为椭圆