python - 是否可以根据对单个 pandas DataFrame 列的查询跨行进行多次更新

Question

我想一次性更新国家名称的数据框

import pandas as pd
df = pd.DataFrame( {'countries': ['United States of America','United Kingdom','Republic of Korea','Netherlands']})
df

输出 1:

我想更新国家名称，但这样做似乎效率不高

df.loc[df['countries']=='United States of America' ,'countries'] = 'USA'
df.loc[df['countries']=='United Kingdom' ,'countries'] = 'UK'
df.loc[df['countries']=='Republic of Korea' ,'countries'] = 'South Korea'
df.loc[df['countries']=='Netherlands' ,'countries'] = 'Holland'

df

上面的工作给我这个输出:

理想情况下，我想用以下内容更新它:

df.loc[df['countries'] in ['United States of America','United Kingdom','Republic of Korea','Netherlands'] 
       ,'countries'] = ['USA','UK','South Korea','Holland']

但是，我遇到了这个错误，我无法通过尝试使用 .any() 函数或我迄今为止尝试过的任何其他方法来克服它。

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

如果您能帮助我们更有效地使用相应的列表更新多个有序的资格，我们将不胜感激。

Answer 1

使用带有pd.DataFrame.replace的字典:

dd = {'United States of America':'USA', 
      'United Kingdom':'UK',
      'Republic of Korea':'South Korea',
      'Netherlands':'Holland'}

df.replace(dd)

输出:

     countries
0          USA
1           UK
2  South Korea
3      Holland