R/z_scored_group_mean.R

In psycCleaning: Data Cleaning for Psychological Analyses

#' Z scored with with respect to the group mean
#' 
#' This function will compute group-mean-centered scores, and then z-scored the group-mean-centered scores with respect to the grand mean.
#' 
#' @param data A data.frame or a data.frame extension (e.g. a tibble).
#' @param cols Columns that need to be centered. See `dplyr::dplyr_tidy_select` for available options. 
#' @param group the grouping variable. If you need to pass multiple group variables, try to use quos(). Passing multiple group variables is not tested.
#' @param keep_original default is `FALSE`. Set to `TRUE` to keep original columns
#' 
#' @export
#' @return
#' return a dataframe with a group-mean centered columns that are z-scored with respect to the grand mean. 
#'
#' @examples 
#' z_scored_group_mean(iris, dplyr::ends_with("Petal.Width"), "Species")
z_scored_group_mean = function(data,cols,group,keep_original=TRUE) {
  cols = enquo(cols)
  group = enquo(group)
  original_df = data %>% dplyr::select(!!cols)
  
  return_df = data %>%
    dplyr::group_by(dplyr::across(!!group)) %>%
    dplyr::mutate(dplyr::across(!!cols, function(x) { (x - mean(x,na.rm = TRUE))})) %>% 
    dplyr::ungroup() %>% 
    dplyr::mutate(dplyr::across(!!cols, function(x) { (x - mean(x,na.rm = TRUE))/stats::sd(x,na.rm = TRUE)})) %>% 
    dplyr::rename_with(~ paste(.,'_group_z',sep = ''),!!cols) %>% 
    dplyr::ungroup()
  if (keep_original == TRUE) {
    return_df = dplyr::bind_cols(return_df,original_df)
  }
  return(return_df)
}