在Pandas中使用groupby执行多个case when语句的有效方法

import pandas as pd
import numpy as np

# 创建一个示例数据集
data = {'Name': ['Tom', 'Nick', 'John', 'Tom', 'John'],
        'Subject': ['Math', 'English', 'Math', 'English', 'Math'],
        'Score': [80, 70, 90, 85, 95]}
df = pd.DataFrame(data)

# 定义条件列表和选择列表
conditions = [
    (df['Subject'] == 'Math') & (df['Score'] >= 90),
    (df['Subject'] == 'Math') & (df['Score'] < 90),
    (df['Subject'] == 'English') & (df['Score'] >= 80),
    (df['Subject'] == 'English') & (df['Score'] < 80)
]
choices = ['优秀', '良好', '及格', '不及格']

# 使用np.select函数进行条件选择
df['Grade'] = np.select(conditions, choices, default='未知')

# 打印结果
print(df)

   Name  Subject  Score Grade
0   Tom     Math     80    良好
1  Nick  English     70  不及格
2  John     Math     90    优秀
3   Tom  English     85    及格
4  John     Math     95    优秀