order {base}R Documentation

Ordering Permutation

Description

order returns a permutation which rearranges its first argument into ascending order, breaking ties by further arguments. sort.list is the same, using only one argument but allowing partial sorting.

Usage

order(..., na.last = TRUE)
sort.list(x, partial, na.last = TRUE)

Arguments

... a sequence of vectors, all of the same length.
x a vector.
partial vector of indices for partial sorting.
na.last for controlling the treatment of NAs. If TRUE, missing values in the data are put last; if FALSE, they are put first; if NA, they are removed. Currently, TRUE is the only possible value.

Details

In the case of ties in the first vector, values in the second are used to break the ties. If the values are still tied, values in the later arguments are used to break the tie (see the first example).

NA values are treated as greater than any other values so that permutations returned by order move NA values to the top end of the array. Other options are not (yet) implemented in R.

partial is supplied for compatibility with other implementations of S, but the sorting is always complete.

See Also

sort and rank.

Examples

(ii <- order(x <- c(1,1,3:1,1:4,3), y <- c(9,9:1), z <-c(2,1:9)))
## 6  5  2  1  7  4 10  8  3  9
rbind(x,y,z)[,ii] # shows the reordering (ties via 2nd & 3rd arg)

## rearrange matched vectors so that the first is in ascending order
x <- c(5:1, 6:8, 12:9)
y <- (x - 5)^2
o <- order(x)
rbind(x[o], y[o])