你甚至不需要 ifelse（）如果你想要的只是一个指示符，要删除与否。

You don't even need the ifelse() if all you want is an indicator of which to remove or not.

ind <- (Month == "11") &
           ((ID == "1" & Year == "2006") | (ID == "2" & Year == "2007"))

ind 如果月将包含TRUE >是11，如果其他两个子条款中的任何一个是 TRUE 。

ind will contain a TRUE if Month is "11" and if either of the other two subclauses is TRUE.

然后你可以通过 [或！ind 删除这些样本code> subset（）。

Then you can drop those sample using !ind in any subset operation via [ or subset().

dat <- data.frame(ID = rep(c("1","2"), each = 72),
                  Year = rep(c("2006","2007","2008"), each = 24),
                  Month = rep(as.character(1:12), times = 3))
ind <- with(dat, (Month == "11") & ((ID == "1" & Year == "2006") |
                                    (ID == "2" & Year == "2007")))
ind
dat2 <- dat[!ind, ]

这给出了

R> ind
  [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE FALSE
 [13] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE FALSE
 [25] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [37] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [49] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [61] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [73] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [85] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [97] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE FALSE
[109] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE FALSE
[121] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[133] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
R>     dat2 <- dat[!ind, ]
R> nrow(dat)
[1] 144
R> nrow(dat2)
[1] 140

这在示例数据方面是正确的/

which is correct in terms of the example data/