简而言之,我该怎么办?
structure(list(id = c(1, 2, 3, 4, 5, 6), user = c(1, 1, 1, 2,
2, 2), value = c(1, 3, 5, 2, 5, 9)), .Names = c("id", "user",
"value"), row.names = c(NA, -6L), class = "data.frame")
to this?
structure(list(id = c(1, 3, 4, 6), user = c(1, 1, 2, 2), value = c(1,
5, 2, 9)), .Names = c("id", "user", "value"), row.names = c(NA,
-4L), class = "data.frame")
意思是,对于每个用户,只需要保留最低和最高对应的两行value
.
我想要一个使用的解决方案dplyr
, 如果可能的话。否则,任何解决方案都可以。