如何根据python pandas中与前一行的差异来移动列值？

import pandas as pd

# 创建一个示例DataFrame
data = {'A': [1, 2, 3, 4, 5],
        'B': [10, 20, 30, 40, 50]}
df = pd.DataFrame(data)

# 计算与前一行的差异
diff = df['A'].diff()

# 将B列的值向上移动一行
df['B'] = df['B'].shift(-1)

# 将A列的值根据与前一行的差异移动
df['A'] = df['A'] + diff

print(df)

     A     B
0  1.0  20.0
1  3.0  30.0
2  5.0  40.0
3  7.0  50.0
4  NaN   NaN