Pandas 中的 Str.contain 用于所有值为 NaN 的列

Question

I'm going through a Dataframe generated from reading a PDF file. When reading the file, it may happen that one of the columns contains only NaN values.

I need to search for a string in all column, but running str.contains on the column with all NaN results in AttributeError: Can only use.str accessor with string values!

The code below results in the error. Change one of the NaN values to a string though, and it works. How do I get around this?

d = {'col': [np.nan, np.nan, np.nan, np.nan, np.nan]}
df = pd.DataFrame(data=d)
df['col'].str.contains('Total Due This Invoice - USD', na=False)

Answer 1

One idea is replace missing values to some non match string value, eg here empty string:

m = df['col'].fillna('').str.contains('Total Due This Invoice - USD')
print (m)
0    False
1    False
2    False
3    False
4    False
Name: col, dtype: bool