sfsmisc (version 0.9-4)

uniqueL: A Reversable Version of unique()

Description

A version of unique keeping enough information to reverse (or invert) to the original data.

Usage

uniqueL(x, isuniq = !duplicated(x))

Arguments

x

numeric vector, of length n, say.

isuniq

logical vector of the same length as x. For the reversion to work this should select at least all unique values of x.

Value

• list of two components,
• ix
  integer vector of indices
• xU
  vector of values from x
• such that both x[isuniq] === xU and xU[ix] === x.

See Also

unique, duplicated.

Examples

x0 <- c(1:3,2:7,8:4)
 str(r0 <- uniqueL(x0))
 with(r0, xU[ix]) ## == x0 !
<testonly>for(n in 1:100) {
   x0 <- round((1+rpois(1,lam=1))*rnorm(40))
   r0 <- uniqueL(x0)
   stopifnot(sort(unique(x0)) == r0$xU,
	     with(r0, xU[ix]) == x0)
 }</testonly>