如果索引不同,如何停止切换大熊猫中的列

您可以快速完成此任务 np.where

import pandas as pd
import numpy as np

# Create Example Data
df = pd.DataFrame({
    'Id':[1, 1, 1, 2, 2, 2],
    'A': [6, 4, 11, 7, 9, 12]
})

# Where
df['Difference'] = np.where(
    # The Id's are the same
    df['Id'] == df['Id'].shift(-1), 
    # Take the difference
    df['A'] - df['A'].shift(-1), 
    # Else, np.NaN
    np.NaN
)

输出:

    A  Id  Difference
0   6   1         2.0
1   4   1        -7.0
2  11   1         NaN
3   7   2        -2.0
4   9   2        -3.0
5  12   2         NaN

你可以先 groupby 'id' :

In [156]: df.assign(
     ...:   new_col=df.groupby('id').diff(-1)
     ...: )
Out[156]: 
    A  id  new_col
0   6   1      2.0
1   4   1     -7.0
2  11   1      NaN
3   7   2     -2.0
4   9   2     -4.0
5  13   2      NaN