python - 替换 Pandas 列中的值

Question

是否可以根据确定某个值是否高于或低于某个阈值且不适用的逻辑来替换 pandas DataFrame 中的值？`

import pandas as pd

df = pd.DataFrame({'date': pd.date_range(start='2015-12-31',
                                       periods=13,
                                      freq='M'),
               'val': [1, 10, 25, -1000, 45, 66, 99, 88,128, 256,512,1024, 2048]}).set_index('date')

所以我想用 N/A 替换任何值 > abs 10

Answer 1

您可以创建一个 bool 掩码来仅设置满足 bool 条件的行，此外您还可以使用 abs测试该值是否为 +/- 10:

In [107]:    
df.loc[df['val'].abs() > 10, 'val' ] = np.NaN
df

Out[107]:
             val
date            
2015-12-31   1.0
2016-01-31  10.0
2016-02-29   NaN
2016-03-31   NaN
2016-04-30   NaN
2016-05-31   NaN
2016-06-30   NaN
2016-07-31   NaN
2016-08-31   NaN
2016-09-30   NaN
2016-10-31   NaN
2016-11-30   NaN
2016-12-31   NaN