python - 为什么无法使用 bool 掩码修改数据框中的值？

Question

例如，我想将“国家/地区”列中的“韩国”更改为“韩国”，但看起来“韩国”仍然保留在那里:

df[df['Country'] == 'Republic of Korea']['Country'] = 'South Korea'
df[df['Country'] == 'Republic of Korea']['Country']


164    Republic of Korea
Name: Country, dtype: object

Answer 1

您正在处理 copy (slice) of original dataframe 。尝试使用dataframe.loc

df.loc[df['Country'] == 'Republic of Korea', 'Country'] = 'South Korea'

此外，当您运行代码时应该会出现警告:

A value is trying to be set on a copy of a slice from a DataFrame.

Try using .loc[row_indexer,col_indexer] = value instead