Pandas fillna with string values from 2 other columns
Keep using the vectorized operation that you suggested. Notice that the argument can receive a combination from the other instances:
df.MSA.fillna(df.City + "," + df.State, inplace=True)
I have a df with 3 columns, City, State, and MSA. Some of the MSA values are NaN. I would like to fill the MSA NaN values with a concatenation of City and State. I can fill MSA with City using df.MSA_CBSA.fillna(df.City, inplace=True), but some cities in different states have the same name.




City
State
MSA




Chicago
IL
Chicago MSA


Belleville
IL
Nan


Belleville
KS
Nan







City
State
MSA




Chicago
IL
Chicago MSA


Belleville
IL
Belleville IL


Belleville
KS
Belleville KS