我想按type对数据进行分组，这样我必须将Qty和amount进行分组时，我有1个已卖出，1个又卖出了……。对于Date，代码可以保留第二个Date
1 Type Date Qty Price Amount
2 Sold 2018-06-28 20:47:48 UTC 0.0078 667514.96 5206.616688
3 Sold 2018-06-28 20:47:48 UTC 0.0022 667514.96 1468.532912
4 Bought 2018-06-28 20:48:17 UTC 0.01 668624.1841 6686.241841
5 Sold 2018-06-28 20:48:33 UTC 0.005 668424.97 3342.12485
6 Sold 2018-06-28 20:48:35 UTC 0.005 668435.82 3342.1791
7 Bought 2018-06-28 20:48:50 UTC 0.01 667898.67 6678.9867
8 Sold 2018-06-28 20:48:58 UTC 0.01 667881.57 6678.8157
9 Bought 2018-06-28 20:49:54 UTC 0.01 668941.24 6689.4124
10 Bought 2018-06-28 20:57:58 UTC 0.001 668442.05 668.44205
11 Bought 2018-06-28 20:58:31 UTC 0.009 668602.02 6017.41818
12 Sold 2018-06-28 20:58:35 UTC 0.01 668293.98 6682.9398
13 Bought 2018-06-28 20:59:04 UTC 0.01 668626.02 6686.2602
14 Sold 2018-06-28 20:59:43 UTC 0.01 668892.83 6688.9283
15 Bought 2018-06-28 20:59:54 UTC 0.01 669230.64 6692.3064
16 Sold 2018-06-28 21:02:40 UTC 0.01 668746.96 6687.4696
17 Bought 2018-06-28 21:02:49 UTC 0.01 668019.58 6680.1958
18 Sold 2018-06-28 21:03:43 UTC 0.01 667884.01 6678.8401
19 Bought 2018-06-28 21:08:13 UTC 0.004 668007.2834 2672.029133
例如，首先要对第2行和第3行进行分组，然后离开第4行，对第5行和第6行进行分组。并且9、10和11也必须进行分组。
这是一个例子
1 Type Date Qty Amount
2&3 Sold 2018-06-28 20:47:48 sum(2&3) sum(2&3)
4 Bought 2018-06-28 20:48:17 0.01 6686.241841
5&6 Sold 2018-06-28 20:48:33 sum(5&6) sum(5&6)
7 Bought 2018-06-28 20:48:50 0.01 6678.9867
8 Sold 2018-06-28 20:48:58 0.01 6678.8157
9$10&11 Bought 2018-06-28 20:49:54 sum(9&10&11) sum(9&10&11)
12 Sold 2018-06-28 20:58:35 0.01 6682.9398
...
我已经尝试过dplyr，但如果有人有主意，还是没有成功，谢谢。