Pandas枢轴并添加到同一数据框？

Question

如果我有一个类似于以下内容的数据框

Year Month Date Country Counts
2010 01    01   USA     10
2010 01    01   Canada  20
2010 01    01   Russia  13
2010 01    01   Brazil  14
2010 01    01   China   21
2010 01    02   USA     11
2010 01    02   Canada  21
2010 01    02   Russia  14
2010 01    02   Brazil  15
2010 01    02   China   22

如何转换为以下内容？

Year Month Date Country Counts USA Canada Russia Brazil China
2010 01    01   USA     10     10  0      0      0      0
2010 01    01   Canada  20     0   20     0      0      0
2010 01    01   Russia  13     0   0      13     0      0
2010 01    01   Brazil  14     0   0      0      14     0
2010 01    01   China   21     0   0      0      0      21
2010 01    02   USA     10     11  0      0      0      0
2010 01    02   Canada  20     0   21     0      0      0
2010 01    02   Russia  13     0   0      14     0      0
2010 01    02   Brazil  14     0   0      0      15     0
2010 01    02   China   21     0   0      0      0      22

Answer 1

用途：

df1 = (df.join(df.set_index('Country', append=True)['Counts']
                 .unstack(fill_value=0)
                 .reindex(df['Country'].unique(), axis=1)))
print (df1)
   Year  Month  Date Country  Counts  USA  Canada  Russia  Brazil  China
0  2010      1     1     USA      10   10       0       0       0      0
1  2010      1     1  Canada      20    0      20       0       0      0
2  2010      1     1  Russia      13    0       0      13       0      0
3  2010      1     1  Brazil      14    0       0       0      14      0
4  2010      1     1   China      21    0       0       0       0     21
5  2010      1     2     USA      11   11       0       0       0      0
6  2010      1     2  Canada      21    0      21       0       0      0
7  2010      1     2  Russia      14    0       0      14       0      0
8  2010      1     2  Brazil      15    0       0       0      15      0
9  2010      1     2   China      22    0       0       0       0     22