R/operator.EAMutatorInsertion.R

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

#' @title
#' Insertion mutator.
#'
#' @description
#' The Insertion mutation operator selects a position random and inserts it at
#' a random position.
#'
#' @param ind [\code{integer}]\cr
#'   Permutation of integers, i.e., vector of integer values.
#' @return [\code{integer}]
#' @family mutators
#' @export
EAMutatorInsertion = function() {
  EAMutator$new(
    name = "Insertion mutation",
    representations = "permutation",
    params = list(),
    fun = function(ind) {
      n = length(ind)
      # select a random position and insert it at another random location
      idx = sample(seq(n), size = 2L)
      # idx[1] is the selected position
      # idx[2] is the destination
      # equality is impossible, since replace = FALSE in sample above
      tmp = ind[idx[1]]
      # determine shift direction
      offset = if (idx[1] < idx[2]) (1) else (-1)
      ind[idx[1]:(idx[2] - offset)] = ind[(idx[1] + offset):idx[2]]
      ind[idx[2]] = tmp
      return(ind)
    }
  )
} # EAMutatorInsertion