R/getfit.R

In mice: Multivariate Imputation by Chained Equations

#' Extract list of fitted models
#'
#' Function \code{getfit()} returns the list of objects containing the repeated analysis
#' results, or optionally, one of these fitted objects. The function looks for
#' a list element called \code{analyses}, and return this component as a list with
#' \code{mira} class. If element \code{analyses} is not found in \code{x}, then
#' it returns \code{x} as a \code{mira} object.
#'
#' No checking is done for validity of objects. The function also processes
#' objects of class \code{mitml.result} from the \code{mitml} package.
#'
#' @param x An object of class \code{mira}, typically produced by a call
#' to \code{with()}.
#' @param i An integer between 1 and \code{x$m} signalling the index of the
#' repeated analysis. The default \code{i= -1} return a list with all analyses.
#' @param simplify Should the return value be unlisted?
#' @return If \code{i = -1} an object of class \code{mira} containing
#' all analyses. If \code{i} selects one of the analyses, then it return
#' an object whose with class inherited from that element.
#' @author Stef van Buuren, 2012, 2020
#' @seealso \code{\link[=mira-class]{mira}}, \code{\link{with.mids}}
#' @keywords manip
#' @examples
#' imp <- mice(nhanes, print = FALSE, seed = 21443)
#' fit <- with(imp, lm(bmi ~ chl + hyp))
#' f1 <- getfit(fit)
#' class(f1)
#' f2 <- getfit(fit, 2)
#' class(f2)
#' @export
getfit <- function(x, i = -1L, simplify = FALSE) {
  if (is.null(x$analyses)) {
    ra <- x
  } else {
    ra <- x$analyses
  }
  if (i != -1L) {
    return(ra[[i]])
  }
  if (simplify) ra <- unlist(ra)
  class(ra) <- c("mira", "list")
  ra
}

#' Extract estimate from \code{mipo} object
#'
#' \code{getqbar} returns a named vector of pooled estimates.
#'
#' @param x An object of class \code{mipo}
#' @export
getqbar <- function(x) {
  if (!is.mipo(x)) stop("Not a mipo object")
  qbar <- x$pooled$estimate
  # note: not supported: component/y.values
  names(qbar) <- x$pooled$term
  qbar
}