python - 如何用条件拆分 Pandas 列

Question

我有一个日志 df，在那个 df 中我有列描述。看起来像。

Description
Machine x : Turn off
Another action here
Another action here
Machine y : Turn off
Machine x : Turn on
Another action here

我只需要用“:”分割行

喜欢:

Description               Machine           Action
Machine x : Turn off      Machine x         Turn off
Another action here
Another action here
Machine y : Turn off      Machine y         Turn off
Machine x : Turn on       Machine x         Turn on
Another action here

我已经试过了:

s = df["Description"].apply(lambda x:x.split(":"))
df["Action"] = s.apply(lambda x: x[1])
df["Machine"] = s.apply(lambda x: x[0])

还有一些带有“startswith”的东西。

Answer 1

您可以将 str.extract 与合适的 regex 一起使用。这将找到 : 周围的所有值(同时去除冒号周围的空格):

df[['Machine', 'Action']] = df.Description.str.extract('(.*) : (.*)',expand=True)

>>> df
            Description    Machine    Action
0  Machine x : Turn off  Machine x  Turn off
1   Another action here        NaN       NaN
2   Another action here        NaN       NaN
3  Machine y : Turn off  Machine y  Turn off
4   Machine x : Turn on  Machine x   Turn on
5   Another action here        NaN       NaN

# df[['Machine', 'Action']] = df.Description.str.extract('(.*) : (.*)',expand=True).fillna('')