以下代码生成一个pdf文件，该文件由循环barplot在数据帧上馈送。我的目标是在栏上注释值。我已经尝试过多次监视值，但是失败了。我可以在这方面得到任何帮助吗？谢谢
import matplotlib.pyplot as plt
import seaborn as sns
import pandas as pd
from matplotlib.backends.backend_pdf import PdfPages
d = {'index': ['index1', 'index1', 'index2', 'index2'], 'group': ['gr1', 'gr1','gr2','gr2'],
targetscore':[15,15,10,10], 'exam':['old','new','old','new'], 'score':[5,6,7,8]}
df = pd.DataFrame(data = d)
pp = PdfPages('mypath/extraction.pdf')
for i in range(len(df['group'])):
subdf = df[df['group'] == df.iloc[i,1]]
sns.catplot(y = 'score', x = 'group', data = subdf, hue = 'exam', kind = 'bar',
row = 'index', col = 'exam', col_order = ['old', 'new'], height = 3, aspect = 2)
plt.show
pp.savefig(plt.gcf())
pp.close()