permuteLevels: Permute the levels of a factor
In lsr: Companion to "Learning Statistics with R"

Description Usage Arguments Details Value See Also Examples

Apply an arbitrary permutation to the ordering of levels within a factor

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

`x`	The factor to be permuted
`perm`	A vector specifying the permutation
`ordered`	Should the output be an ordered factor?
`invert`	Use the inverse of `perm` to specify the permutation

This is a convenience function used to shuffle the order in which the levels of a factor are specified. It is similar in spirit to the relevel function, but more general. The relevel function only changes the first level of the factor, whereas permuteLevels can apply an arbitrary permutation. This can be useful for plotting data, because some plotting functions will display the factor levels in the same order that they appear within the factor.

The perm argument is a vector of the same length as levels(x), such that perm[k] is an integer that indicates which of the old levels should be moved to position k. However, if invert=TRUE, the inverse permutation is applied: that is, perm[k] is an integer specifying where to move the k-th level of the original factor. See the examples for more details.

Returns a factor with identical values, but with the ordering of the factor levels shuffled.

factor, order, relevel

# original factor specifies the levels in order: a,b,c,d,e,f
x <- factor( c(1,4,2,2,3,3,5,5,6,6), labels=letters[1:6] )
print(x)

# apply permutation (5 3 2 1 4 6)... i.e., move 5th factor level (e)
# into position 1, move 3rd factor level (c) into position 2, etc
permuteLevels(x,perm = c(5,3,2,1,4,6))

# apply the inverse of permutation (5 3 2 1 4 6)... i.e., move 1st
# level (a) into position 5, move 2nd level (b) into position 3, etc
permuteLevels(x,perm = c(5,3,2,1,4,6),invert=TRUE)