假设我有数据框架:
df<-structure(list(predworker = c(1, 1, 1, 1, 1, 3, 3, 3, 3, 3, 4,
4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 8, 8,
8, 8, 8, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10,
11, 11, 11, 11, 11
), worker = c(1, 14, 11, 19, 13, 23, 3, 15, 20,