如何从透视操作中合并回数据帧？

import pandas as pd

# 创建示例数据框
data = {'Name': ['Alice', 'Bob', 'Charlie', 'Alice', 'Bob', 'Charlie'],
        'Subject': ['Math', 'Math', 'Math', 'Science', 'Science', 'Science'],
        'Score': [80, 90, 75, 85, 95, 70]}
df = pd.DataFrame(data)

# 进行透视操作
pivot_df = df.pivot_table(index='Name', columns='Subject', values='Score')

# 将透视结果重新转换回原始数据框
melt_df = pivot_df.reset_index().melt(id_vars='Name', value_name='Score').dropna()

# 打印结果
print(melt_df)

      Name  Subject  Score
0    Alice     Math   80.0
1      Bob     Math   90.0
2  Charlie     Math   75.0
3    Alice  Science   85.0
4      Bob  Science   95.0
5  Charlie  Science   70.0