pandas - Mapping Python dictionary with multiple keys into dataframe with multiple columns matching keys

Question

I have a dictionary that I would like to map onto a current dataframe and create a new column. I have keys in a tuple, which map onto two different columns in my dataframe.

dct = {('County', 'State'):'CountyType'}
df = pd.DataFrame(data=['County','State'])

I would like to create a new column, CountyType, using dict to map onto the two columns in df. However, doing the following gives me an error. How else could this be done?

df['CountyType'] = (list(zip(df.County,df.State)))
df = df.replace({'CountyType': county_type_dict)

Answer 1

You can create a MultiIndex from two series and then map. Data from @ALollz.

df['CountyType'] = df.set_index(['County', 'State']).index.map(dct.get)

print(df)

  County  State CountyType
0      A      1        One
1      A      2       None
2      B      1       None
3      B      2        Two
4      B      3      Three