import pandas
df = pd.DataFrame({'AAA' : ["a1","a2","a3","a4","a5","a6","a7"], 'BBB' : ["c1","c2","c2","c2","c3","c3","c1"],'CCC' : [10,11,12,100,50,-30,-50]}); df
df2 = pd.DataFrame({'AAA' : ["a1","a2","a4","a6","a7","a8","a9"], 'BBB' : ["c11","c21","c21","c12","c13","c13","c11"],'CCC' : [10,11,12,100,50,-30,-50]}); df2