使用groupby从Dataframe绘制堆叠条形图

import pandas as pd
import matplotlib.pyplot as plt

data = {'Country': ['USA', 'USA', 'China', 'China', 'India', 'India'],
        'Year': [2010, 2015, 2010, 2015, 2010, 2015],
        'Population': [309, 322, 1339, 1376, 1233, 1311]}
df = pd.DataFrame(data)

grouped = df.groupby(['Country', 'Year']).sum()

stacked = grouped.unstack()

stacked.plot(kind='bar', stacked=True)
plt.xlabel('Year')
plt.ylabel('Population')
plt.title('Population by Country and Year')
plt.legend(loc='upper left')
plt.show()