merge dataframes

[klllmmm]

Hope this helps;

df1 = pd.DataFrame(data = {'pais':['Chile','Chile','Chile'],
                             'año':[2000,2001,2002],
                             'cantidad':[10,11,12],})
    
df2 = pd.DataFrame(data = {'pais':['Chile','Chile','Chile','Chile','Chile'],
                             'año':[1999,2000,2001,2002,2003],
                             'cantidad':[0,0,0,0,0],})

df1=df1.set_index(['pais','año'])
df2=df2.set_index(['pais','año'])    

df1_2 = df1.add(df2,fill_value=0)
df1_2.reset_index()

Output:
Out[280]: 
    pais   año  cantidad
0  Chile  1999       0.0
1  Chile  2000      10.0
2  Chile  2001      11.0
3  Chile  2002      12.0
4  Chile  2003       0.0