我写了一个基于条件提取行的函数，如下所示：

ex <- function(x, y){
  Sname <- paste0("A00-",x)
  state <- paste0(x, "_state")
  test1 <- paste0(x, "_test1")
  test2 <- paste0(x, "_test2")
  temp <- dt[c("ID",state,test1,test2)
  temp[,test1] <- ifelse(temp[,state] >= y, temp[,test1] ,"NA")
  head(temp)]
  }

我的表有列

> names(dt)
 [1] "ID"            "A_test1"       "A_test2"       "A_state"     "A_anoo"     
 [6] "B_test1"       "B_test2"       "B_state"       "B_anoo"      "C_test1"      
[11] "C_test2"       "C_state"       "C_anoo"

当我使用我的函数ex(x = "B", y= 0.2)时，我会得到这个错误：

>   temp <- dt[c("ID",state,test1,test2)]
Error in `[.data.table`(dt, c("ID",state,test1,test2), ) : 
  When i is a data.table (or character vector), the columns to join by must be specified using 'on=' argument (see ?data.table), by keying x (i.e. sorted, and, marked as sorted, see ?setkey), or by sharing column names between x and i (i.e., a natural join). Keyed joins might have further speed benefits on very large data due to x being sorted in RAM.

如果有人能帮我，那就太好了。谢谢。