R/df2milist.R

In miceafter: Data and Statistical Analyses after Multiple Imputation

#'  Turns a data frame with multiply imputed data into
#'  an object of class 'milist'
#'
#' \code{df2milist} Turns a data frame of class 'data.frame', 'tbl_df'
#'  or 'tbl' (tibble) into an object of class 'milist' to be further used
#'  by 'miceafter::with'
#'
#' @param data an object of class 'data.frame', 'tbl_df' or 'tbl'
#' (tibble).
#' @param impvar A character vector. Name of the variable that
#'  distinguishes the imputed datasets.
#' @param keep if TRUE the grouping column is kept, if FALSE (default)
#'  the grouping column is not kept.
#'
#' @return an object of class 'milist' (Multiply Imputed Data list)
#'
#' @author Martijn Heymans, 2021
#'
#' @export
df2milist <- function(data, impvar, keep=FALSE){
  if (!any(class(data)=="data.frame"))
    stop("object must be of class 'data.frame'")
  if(!impvar %in% names(data))
    stop("Variable defined as 'impvar' not in dataset")

  imp_list <- data %>%
    group_split(get(impvar), .keep = keep)
  if (length(imp_list)<2)
    stop("Data must contain more than 1 imputed dataset")
  class(imp_list) <- "milist"
  return(imp_list)
}