Calculate frequency.

freq.r

freq <- function(df, ...){
  df %<>%
    group_by_(...) %>%
    summarise(count = n()) %>%
    arrange_(.dots = ...) %>%
    ungroup() %>%
    mutate(
      cum_count = cumsum(count),
      percent = count / sum(count),
      cum_percent = cumsum(percent)
    )
  return(df)
}