我有以下数据帧:
Year Country medal no of medals
1896 Afghanistan Gold 5
1896 Afghanistan Silver 4
1896 Afghanistan Bronze 3
1896 Algeria Gold 1
1896 Algeria Silver 2
1896 Algeria Bronze 3
我想要这样.
Year Country Gold Silver Bronze
1896 Afghanistan 5 4 3
1896 Algeria 1 2 3
Stack/Unstack似乎不起作用.