python - String extract with loc

Question

I am tryin to format bibliography in a dataframe. Basically, for a column named "Bibliography", I want to extract the titles, sometimes delimited by and sometimes delimited by "

Now when I use

df.loc[df['Bibliography'].str.extract(?<=&quot;)(.*?)(?=,&quot;)

It correctly extracts the titles delimited by " (but will produce NaN for titles delimited by )

So I tried applying str.extract over a slice of the data frame using .loc

df.loc[df['Bibliography'].str.contains('&quot;'),'Bibliography']=df.loc[df['Bibliography'].str.contains('&quot;'),'Bibliography'].str.extract(r'(?<=&quot;)(.*?)(?=,&quot;)')

But this results in NaN. I can't figure out why I can't use extract over a slice of the data frame.

Answer 1

等待大神解答