R/OsakaCityChoropleth.R

In yutannihilation/choroplethrOsakaCity: Draw Choropleth Maps of Osaka city

#' A Choropleth Class for Osaka City Map
#'
#' @name osakaCityChoropleth
#' @importFrom ggplot2 geom_text aes
#' @importFrom R6 R6Class
#' @examples
#' \dontrun{
#' library(ggplot2)
#' library(dplyr)
#'
#' csv_file <- tempfile(fileext = ".csv")
#' download.file("https://raw.githubusercontent.com/yutannihilation/osaka_age_composition/master/osaka_age_composition.csv",
#'            destfile = csv_file, method = "curl")
#'
#' age_comp.df <- read.csv(csv_file, header = TRUE, stringsAsFactors = FALSE, fileEncoding = "UTF-8") %>%
#'   group_by(district) %>%
#'   summarise(value = sum(age * total)/sum(total)) %>%
#'   mutate(region = to_osaka_ward_code(district))
#'
#' osaka_city_chropleth(age_comp.df, title = "Age Composition") + coord_equal()
#' }
#' @export
osakaCityChoropleth <- R6Class(
  "osakaCityChoropleth",
  inherit = choroplethr:::Choropleth,
  public = list(
    show_labels = TRUE,

    initialize = function(user.df)
    {
      data(osaka_city.map, package = "choroplethrOsakaCity")
      super$initialize(osaka_cify.map, user.df)
    },

    render = function()
    {
      choropleth = super$render()

      # by default, add labels for the lower 48 states
      if (self$show_labels) {
        data(osaka_city.label, package = "choroplethrOsakaCity")

        choropleth = choropleth +
          geom_text(data = osaka_city.label, aes(long, lat, label = region_name, group = NULL), colour = 'black')
      }

      choropleth
    }
  )
)

#' @rdname osakaCityChoropleth
#' @export
osaka_city_chropleth <- function(df, title = "", legend = "", num_colors = 7, zoom = NULL){
  c        <- osakaCityChoropleth$new(df)
  c$title  <- title
  c$legend <- legend
  c$set_num_colors(num_colors)
  c$set_zoom(zoom)
  c$render()
}