Groupby并选择每个组的第一个、第二个和第四个成员？

import pandas as pd

# 假设数据集存储在DataFrame中，包含列：group, name
data = pd.DataFrame({'group': ['A', 'A', 'B', 'B', 'B', 'C', 'C'],
                     'name': ['John', 'Alice', 'Bob', 'Charlie', 'David', 'Emma', 'Frank']})

# 使用Groupby操作按照组别进行分组
grouped = data.groupby('group')

# 遍历每个组，选择第一个、第二个和第四个成员
for group, group_data in grouped:
    # 选择第一个成员
    first_member = group_data.iloc[0]['name']
    print(f"Group {group}: First member - {first_member}")
    
    # 选择第二个成员
    second_member = group_data.iloc[1]['name']
    print(f"Group {group}: Second member - {second_member}")
    
    # 选择第四个成员
    fourth_member = group_data.iloc[3]['name']
    print(f"Group {group}: Fourth member - {fourth_member}")