Permute the levels of a factor

Reorder the levels of a factor into any order you specify.

Usage

permuteLevels(x, perm, ordered = is.ordered(x), invert = FALSE)

Arguments

x

A factor.

perm

An integer vector of the same length as nlevels(x). When invert = FALSE (the default), perm[k] gives the index of the old level that should appear in position k of the new ordering. When invert = TRUE, perm[k] gives the new position to assign to the k-th old level.

ordered

Set to TRUE to return an ordered factor. Defaults to is.ordered(x), preserving the ordered status of the input.

invert

Set to TRUE to apply the inverse of perm. See the perm description above and the examples below.

Value

A factor with the same values as x but with the levels in the new order specified by perm.

Details

Similar to relevel, but more general: relevel can only move one level to the front, whereas permuteLevels can place the levels in any order. This is useful when you want to control the order in which levels appear on a plot axis or in a table.

See also

factor, relevel, order

Examples

# factor with levels a, b, c, d, e, f (in that order)
x <- factor(c(1, 4, 2, 2, 3, 3, 5, 5, 6, 6), labels = letters[1:6])
levels(x)
#> [1] "a" "b" "c" "d" "e" "f"

# move level e to position 1, c to position 2, b to 3, a to 4, d to 5, f to 6
permuteLevels(x, perm = c(5, 3, 2, 1, 4, 6))
#>  [1] a d b b c c e e f f
#> Levels: e c b a d f

# using invert = TRUE: move level a to position 5, b to 3, c to 2, etc.
permuteLevels(x, perm = c(5, 3, 2, 1, 4, 6), invert = TRUE)
#>  [1] a d b b c c e e f f
#> Levels: d c b e a f