stp <- function(x,
                s = c("m","med","sd","riq","min","max"),
                digits = 3,
                na.rm = TRUE){

  f <- list(
    m   = mean,
    med = median,
    sd  = sd,
    riq = IQR,
    min = min,
    max = max
  )

  s <- match.arg(tolower(s), choices = names(f), several.ok = TRUE)

  out <- vapply(s, function(k) f[[k]](x, na.rm = na.rm), numeric(1))
  round(setNames(out, s), digits)
}


stp_add <- function(lista,
                    x,
                    var,
                    s = c("m","med","sd","riq","min","max"),
                    digits = 3,
                    na.rm = TRUE,
                    sep = "_"){

  vals <- stp(x, s = s, digits = digits, na.rm = na.rm)
  names(vals) <- paste0(names(vals), sep, var)
  lista[names(vals)] <- as.list(vals)
  lista
}