我有一张这样的表：
+------+-----------+
|caseID|groupVarian|
+------+-----------+
|1 |A,B,C,D,E |
+------+-----------+
|2 |A,B,N,O,P |
+------+-----------+
|3 |A,B,N,O,P |
+------+-----------+
|4 |A,B,C,D,F |
+------+-----------+
|5 |A,B,C,D,E |
+------+-----------+
我想获得一个新列nameVarian，以便相同的groupVarian值具有相同的排名nameVarian（例如：v1、v2 等）。但是，nameVarian分配给特定对象的值groupVarian应按照 的顺序caseID（按照它们出现在表中的顺序）。
输出应该是这样的：
+------+-----------+----------+
|caseID|groupVarian|namevarian
+------+-----------+----------+
|1 |A,B,C,D,E |v1 |
+------+-----------+----------+
|2 |A,B,N,O,P |v2 |
+------+-----------+----------+
|3 |A,B,N,O,P |v2 |
+------+-----------+----------+
|4 |A,B,C,D,F |v3 |
+------+-----------+----------+
|5 |A,B,C,D,E |v1 |
+------+-----------+----------+