lsr (version 0.5.2)

permuteLevels: Permute the levels of a factor

Description

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

Usage

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

Arguments

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

Value

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

Details

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.

See Also

factor, order, relevel

Examples

# NOT RUN {
# 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)

# }