Toralf Kirsten <[EMAIL PROTECTED]> writes:
> Hi all,
> I'm looking for an efficient solution (speed and memory) for the
> following problem:
> Given
> - a data.frame x containing numbers of type double
> with nrow(x)>ncol(x) and unique row lables and
> - a character vector y containing a sorted order labels
>
> Now, I'd like to sort the rows of the data.frame x w.r.t. the order of
> labels in y.
>
> example:
> x <- data.frame(c(1:4),c(5:8))
> row.names(x)<-LETTERS[1:4]
> y <- c("C","A","D","B")
>
>
> My current solution is like this:
> if(!is.null(y) && is.vector(y)) {
> nObj <- length(y)
> for (i in 1:nObj) {
> sObj <- y[i]
> k <- c(1:nrow(x))[row.names(x)==sObj]
> if (i != k) {
> names <- row.names(x)
> tObj <- row.names(x[i,])
> temp <- x[i,]
> x[i,] <- x[k,]
> x[k,] <- temp
> names[i] <- sObj
> names[k] <- tObj
> row.names(x) <- names
> }
> }
> }
>
> But I'm not happy with it because it is not really efficient. Any
> other suggestions are welcome!
Anything wrong with x[y,] ???
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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