R/addnulldist.R

In hamsamilton/cgms.analysis: Functions for CGMS analysis

#' Null distribution generator
#'
#' This function generates a null distribution by scrambling the time values on glucose measurements from a cgms.df object
#' @param df input dataframe
#' @keywords nulldistribution generation
#' @export
#' @examples cgms.df %>% addnulldist()
#'

#by resampling historic_glucose at each unique time and append to input df
addnulldist <- function(df) {
  sampledf <- sample(df$historic_glucose,size= length(unique(df$time_past_start)), replace = T)
  rdf <- df %>% dplyr::distinct(time_past_start,.keep_all = T)
  rdf$historic_glucose <- sampledf
  rdf <- rdf %>%
    dplyr::mutate_at(c("subjno","subj_id","run_id","Group","Subject","id","Age","Gender","Phase","visit"),
              function(x){
                return("nulldist")
              }
    )
  rdf <- rbind(df,rdf)
  return(rdf)
}