merging pandas dataframes - getting NaNs

Question

I'm trying to merge pandas dataframes to effectively add a column with "FIPS Codes" according to the county and state in their respective columns.

I'm using pd.merge to do this and getting NaNs. What am I doing wrong?

According to https://pandas.pydata.org/pandas-docs/stable/merging.html this should work.

merged = pd.merge(sales, fips, how='left', on=['county', 'state'])

Here is the head() of sales:

And here is the head() of fips:

And this is the merged result (with NaNs in the final fips column):

Thanks!

Answer 1

Standardise the state names across both dataframes. In sales, the state names are abbreviated, in fips the full name is used.