Мне нужно было назначить "второй" id для группировки некоторых значений внутри моего исходного id. это мои данные образца:
dt<-structure(list(id = c("aaaa", "aaaa", "aaas", "aaas", "bbbb", "bbbb"),
period = c("start", "end", "start", "end", "start", "end"),
date = structure(c(15401L, 15401L, 15581L, 15762L, 15430L, 15747L), class = c("IDate", "Date"))),
class = c("data.table", "data.frame"),
.Names = c("id", "period", "date"),
sorted = "id")
> dt
id period date
1: aaaa start 2012-03-02
2: aaaa end 2012-03-05
3: aaas start 2012-08-21
4: aaas end 2013-02-25
5: bbbb start 2012-03-31
6: bbbb end 2013-02-11
column id необходимо сгруппировать (используя то же значение в say id2) в соответствии с этим списком:
> groups
[[1]]
[1] "aaaa" "aaas"
[[2]]
[1] "bbbb"
Я использовал следующий код, который, кажется, работает, дает следующее warning:
> dt[, id2 := which(vapply(groups, function(x,y) any(x==y), .BY[[1]], FUN.VALUE=T)), by=id]
Warning message:
In `[.data.table`(dt, , `:=`(id2, which(vapply(groups, function(x, :
Invalid .internal.selfref detected and fixed by taking a copy of the whole table,
so that := can add this new column by reference. At an earlier point, this data.table has
been copied by R (or been created manually using structure() or similar). Avoid key<-,
names<- and attr<- which in R currently (and oddly) may copy the whole data.table. Use
set* syntax instead to avoid copying: setkey(), setnames() and setattr(). Also,
list (DT1,DT2) will copy the entire DT1 and DT2 (R list() copies named objects),
use reflist() instead if needed (to be implemented). If this message doesn't help,
please report to datatable-help so the root cause can be fixed.
> dt
id period date id2
1: aaaa start 2012-03-02 1
2: aaaa end 2012-03-02 1
3: aaas start 2012-08-29 1
4: aaas end 2013-02-26 1
5: bbbb start 2012-03-31 2
6: bbbb end 2013-02-11 2
может кто-нибудь кратко объяснить природу этого предупреждения и любое возможное последствие окончательных результатов (если таковые имеются)? спасибо
ИЗМЕНИТЬ:
фактический код фактически показывает, когда создается dt и как передается функция, которая дает предупреждение:
f.main <- function(){
f2 <- function(x){
groups <- list(c("aaaa", "aaas"), "bbbb") # actually generated depending on the similarity between values of x$id
x <- x[, id2 := which(vapply(groups, function(x,y) any(x==y), .BY[[1]], FUN.VALUE=T)), by=id]
return(x)
}
x <- f1()
if(!is.null(x[["res"]])){
x <- f2(x[["res"]])
return(x)
} else {
# something else
}
}
f1 <- function(){
dt<-data.table(id = c("aaaa", "aaaa", "aaas", "aaas", "bbbb", "bbbb"),
period = c("start", "end", "start", "end", "start", "end"),
date = structure(c(15401L, 15401L, 15581L, 15762L, 15430L, 15747L), class = c("IDate", "Date")))
return(list(res=dt, other_results=""))
}
> f.main()
id period date id2
1: aaaa start 2012-03-02 1
2: aaaa end 2012-03-02 1
3: aaas start 2012-08-29 1
4: aaas end 2013-02-26 1
5: bbbb start 2012-03-31 2
6: bbbb end 2013-02-11 2
Warning message:
In `[.data.table`(x, , `:=`(id2, which(vapply(groups, function(x, :
Invalid .internal.selfref detected and fixed by taking a copy of the whole table,
so that := can add this new column by reference. At an earlier point, this data.table
has been copied by R (or been created manually using structure() or similar).
Avoid key<-, names<- and attr<- which in R currently (and oddly) may copy the whole
data.table. Use set* syntax instead to avoid copying: setkey(), setnames() and setattr().
Also, list(DT1,DT2) will copy the entire DT1 and DT2 (R list() copies named objects),
use reflist() instead if needed (to be implemented). If this message doesn't help,
please report to datatable-help so the root cause can be fixed.