我有这样的R数据:
row, sessionId, scenarionName, stepName, duration
1, 1001, A, start, 0
2, 1001, A, step1, 2.2
3, 1001, A, step2, 3.0
4, 1001, A, end, 0
5, 1001, A, start, 0
6, 1002, B, start, 0
7, 1002, B, step1, 1.1
8, 1001, A, step1, 1.5
9, 1001, A, step2, 1.8
10, 1001, A, end, 0
11, 1002, B, step2, 2.1