That should do it.
>>> df = pd.DataFrame({'id': [1, 2, 3, 4, 5, 6],
'User': ['User1', 'User1', 'User2', 'User2', 'User3', 'User3'],
'Month': [1, 2, 1, 2, 1, 2],
'NbTweet': [10, 20, 15, 25, 12, 22]})
>>> df1
id User Month NbTweet
0 1 User1 1 10
1 2 User1 2 20
2 3 User2 1 15
3 4 User2 2 25
4 5 User3 1 12
5 6 User3 2 22
>>> df.set_index(['Month','User']).unstack()['NbTweet']
User User1 User2 User3
Month
1 10 15 12
2 20 25 22
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…