R/freq_table.R

In MathieuMarauri/auditdata: Performs a Quality Audit of a Table

#'
#' Helper function for 'qualityCheck'
#'
#' This function creates a frequency table limited to 'max_length' rows.
#'
#' @param x a vector
#' @param max_length the maximum number of rows in the output.
#' @param cum shoulb cumulative frequencies and percentages be given? Default to FALSE
#'
#' @return a frequency table with the top 'max_length' most frequent
#'   modalities and the associated percentage.
#' 
#' @import data.table
#'
freq_table <- function(x, max_length = Inf, cum = FALSE) {
  N <- NULL # for CMD check
  result <- as.data.table(x)[, .N, by = x][
      order(-N),list(
        value = x,
        freq = N,
        percent = round(100 * N / sum(N), digits = 0)
      )]
  if (cum) {
    value <- freq <- percent <- NULL # for CMD check
    result <- result[, list(value, freq, percent, 
                         cum_freq = cumsum(freq), 
                         cum_percent = cumsum(percent))]
  }
  if (nrow(result) > max_length) {
    result <- result[1:max_length, ]
  }
  return(result)
}