R/mice.impute.sample.R

In mice: Multivariate Imputation by Chained Equations

#' Imputation by simple random sampling
#'
#' Imputes a random sample from the observed \code{y} data
#'
#' This function takes a simple random sample from the observed values in
#' \code{y}, and returns these as imputations.
#'
#' @inheritParams mice.impute.pmm
#' @return Vector with imputed data, same type as \code{y}, and of length
#' \code{sum(wy)}
#' @author Stef van Buuren, Karin Groothuis-Oudshoorn, 2000, 2017
#' @references van Buuren S and Groothuis-Oudshoorn K (2011). \code{mice}:
#' Multivariate Imputation by Chained Equations in \code{R}. \emph{Journal of
#' Statistical Software}, \bold{45}(3), 1-67.
#' \doi{10.18637/jss.v045.i03}
#' @keywords datagen
#' @export
mice.impute.sample <- function(y, ry, x = NULL, wy = NULL, ...) {
  if (is.null(wy)) {
    wy <- !ry
  }
  yry <- y[ry]
  if (length(yry) < 1) {
    return(rnorm(sum(wy)))
  }
  if (length(yry) == 1) yry <- rep(yry, 2)
  sample(yry, size = sum(wy), replace = TRUE)
}