R/create_pareto.R

In dtminnick/fdistr: Frequency Distribution Tables

#' Create Pareto Chart
#'
#' \code{create_pareto} generates a Pareto chart using the group, frequency and
#' cumulative frequency columns of a frequency distribution table.
#'
#' @param df Data frame containing a frequency distribution table.
#'
#' @param title Character string; title to be displayed on Pareto chart.  Default
#' is "Pareto Chart".
#'
#' @param subtitle Character string; subtitle to be displayed on chart.  Default
#' is "".
#'
#' @param caption Character string; caption to be displayed on the chart.  Default
#' is "".
#'
#' @param x_label Character string; x axis label to be displayed on the chart.
#' Default is "Groups".
#'
#' @param y_label Character string; y axis label to be displayed on the chart.
#' Default is "Frequency".
#'
#' @return A plot containing a Pareto chart.  If an error or warning occurs,
#' a message will be printed to the console and the function will return NULL.
#'
#' @importFrom ggplot2 aes element_text geom_bar geom_path geom_point
#' geom_text ggplot labs theme
#'
#' @importFrom stats reorder
#'
#' @examples
#' source <- c(1, 1, 1, 1, 2, 2, 2, 3, 3, 4)
#' table <- create_table(source, dec_pos = 3)
#' plot <- create_pareto(table)
#'
#' @export

create_pareto <- function(df,
                          title = "Pareto Chart",
                          subtitle = "",
                          caption = "",
                          x_label = "Groups",
                          y_label = "Count") {

      tryCatch({

            group <- frequency <- cumulative_frequency <- NULL

            scale_right <- tail(df$cumulative_frequency, n = 1) / head(df$count, n = 1)

            g <- ggplot2::ggplot(df, ggplot2::aes(x = stats::reorder(group, -frequency))) +

                  ggplot2::geom_bar(ggplot2::aes(y = count),
                                    fill = "blue",
                                    stat = "identity") +

                  ggplot2::geom_point(ggplot2::aes(y = cumulative_frequency / scale_right),
                                      color = "green",
                                      pch = 16,
                                      size = 1) +

                  ggplot2::geom_path(ggplot2::aes(y = cumulative_frequency / scale_right, group = 1),
                                     colour = "darkgrey",
                                     lty = 3,
                                     size = 0.9) +

                  ggplot2::scale_y_continuous(sec.axis = ggplot2::sec_axis(~.*scale_right, name = "Cumulative (%)")) +

                  ggplot2::theme(axis.text.x = ggplot2::element_text(angle = 0, vjust = 0.6)) +

                  ggplot2::labs(title = title,
                                subtitle = subtitle,
                                caption = caption,
                                x = x_label,
                                y = y_label)

      }, warning = function(w) {

            warning(paste("create_pareto: ", w, sep = ""))

            return(NULL)

      }, error = function(e) {

            stop(paste("create_pareto: ", e, sep = ""))

            return(NULL)

      }, finally = {

      })

      return(g)

}