Pandas 数据框根据条件替换列中的值

Question

I have a column in data frame like this (an simplify example):我在这样的数据框中有一列（一个简化示例）：

col
a
b
c
d
e
f
g

and I want to change the values like this:我想像这样更改值：

col
a
b
other
other
other
other
other

I tried like this:我试过这样的：

df = df.loc[df.col == ("a" or "b"), "col"] = "other"

but it does not work, I have an error:但它不起作用，我有一个错误：

AttributeError: 'str' object has no attribute 'loc'

Any advices?有什么建议吗？

Answer 1

The problem with your code is, that df is changing to type string during the process.您的代码的问题是， df在此过程中正在更改为类型字符串。

There exists a pandas function for this usecase, named pd.where() .这个用例存在一个 pandas function ，名为pd.where() 。

df = df.where(df['col'].isin(['a', 'b']),'other')

Similar result avoiding where() :避免where()类似结果：

df[~df['col'].isin(['a', 'b'])] = 'other'