R/operator.EAMutatorScramble.R

In jakobbossek/ecr3: Evolutionary Computation in R - Version 3

#' @title
#' Scramble mutator.
#'
#' @description
#' The Scramble mutation operator selects two positions within the chromosome at
#' random and randomly intermixes the subsequence between these positions.
#'
#' @param ind [\code{integer}]\cr
#'   Permutation of integers, i.e., vector of integer values.
#' @return [\code{integer}]
#' @family mutators
#' @export
EAMutatorScramble = function() {
  EAMutator$new(
    name = "Scramble mutation",
    representations = "permutation",
    params = list(),
    fun = function(ind) {
      n = length(ind)
      # here we select two distinct positions ...
      idx = sample(seq(n), size = 2L, replace = FALSE)
      # and therefore we do not have the problem to call sample with
      # a single number as parameter x
      ind[idx[1]:idx[2]] = sample(ind[idx[2]:idx[1]])
      return(ind)
    }
  )
} # EAMutatorScramble