Mapping Column Value Based On Another Column In Python

I am trying to change column value depends from the other column along its row then merge it to an existing excel file using the ADSL column as my key. I have a Data like this: ADS

Solution 1:

I believe need map by Series:

df2['Status'] = df2['Status'].map(df1.set_index('Result')['Status'])

If some values are not match is possible replace by original non NaNs values:

df2['Status'] = df2['Status'].map(df1.set_index('Result')['Status']).fillna(df2['Status'])