I have a big dataframe (the following is an example)

I want to subtract values by 60 whenever the country is portugal or UK, the dataframe should look like (Python)

CodePudding user response：

IUUC, use isin on the lowercase country string to check if the values is in a reference list, then slice the dataframe with loc for in place modification:

df.loc[df['country'].str.lower().isin(['portugal', 'uk']), 'value'] -= 60

output:

    country  value
0  portugal     26
1   germany     20
2   belgium     21
3        Uk     21
4  portugal     17
5        UK     27

CodePudding user response：

Use numpy.where:

In [1621]: import numpy as np

In [1622]: df['value'] = np.where(df['country'].str.lower().isin(['portugal', 'uk']), df['value'] - 60, df['value'])

In [1623]: df
Out[1623]: 
    country  value
0  portugal     26
1   germany     20
2   belgium     21
3        Uk     21
4  portugal     17
5        UK     27