import pandas as pd 
df=pd.read_csv('sales.csv')
df['RFMClass']=pd.qcut(df['recency'],[0,0.25,0.5,0.75,1],['4','3','2','1']).astype('str')+pd.qcut(df['frequency'],[0,0.25,0.5,0.75,1],['1','2','3','4']).astype('str')+pd.qcut(df['monetary'],[0,0.25,0.5,0.75,1],['1','2','3','4']).astype('str')
print(df.head(5))
print()  # 默认会输出换行，故print('\n')是空了2行
print(df[df['RFMClass']=='444'].sort_values(by='monetary',ascending=False).reset_index(drop=True).head(5))