R/plot_region.R

In HughParsonage/grattanElectionMaps:

#' Plot region of Australia
#'
#' @param .polygonal.data Polygonal data (of Australia). See \link{draw_electoral_divisions_map}.
#' @param city Which city to plot
#' @param coord_lines Plot grid lines at 0.1 intervals.
#' @param scale_fill_manual_args,scale_fill_gradientn_args A \code{list} of arguments
#'  to pass to \code{scale_fill_manual} or \code{scale_fill_gradientn}.
#' @param polygon_outline_colour The outline of polygons.
#' @param city_inset_scale Scale relative to Australia.
#' @param title (logical) Should a standard \code{ggtitle} be added to each city?
#' @param title.size The base size of the plot, in points.
#' @param base_size,base_family Passed to \code{theme_map}.
#' @importFrom magrittr %>%
#' @import data.table
#' @return A list of three elements, \code{vwidth} the width of the inset on the device, \code{vheight} the height of the inset on the device, and \code{p} the plot.
#' @note This function should not be called directly. It is intended to be used to plot insets on a map generated through \code{\link{draw_electoral_divisions_map}}.

plot_region <- function(.polygonal.data,
                        city = c("PER", "ADL", "MEL", "SYD", "BNE"),
                        coord_lines = c("none", "latlon", "lat", "lon"),
                        scale_fill_manual_args = NULL,
                        scale_fill_gradientn_args = NULL,
                        polygon_outline_colour = "black",
                        city_inset_scale = 15,
                        title = TRUE, 
                        base_size = 25,
                        base_family = "",
                        title.size = 25) {
  city <- match.arg(city)
  coord_lines <- match.arg(coord_lines)

  xlim1 <- cities_coords[[city]][1]
  xlim2 <- cities_coords[[city]][2]
  ylim1 <- cities_coords[[city]][3]
  ylim2 <- cities_coords[[city]][4]

  lon_lines <- seq(from = ceiling(10 * xlim1) / 10, to = floor(10 * xlim2) / 10, by = .1)
  lat_lines <- seq(from = ceiling(10 * ylim1) / 10, to = floor(10 * ylim2) / 10, by = .1)

  ELECT_DIV <- long <- lat <- include.it <- NULL

  the_divisions_to_plot <-
    .polygonal.data %>%
    # Exclude Lord Howe Island and Norfolk Island
    # (When plotting Division of Sydney or Division of Fraser/Fenner)
    .[long < 154] %>%
    .[, include.it := all(data.table::between(long, xlim1, xlim2),
                          data.table::between(lat , ylim1, ylim2)),
      by = "ELECT_DIV"] %>%
    as.data.table(.) %>%
    .[as.logical(include.it)]

  # Now we have determined the divisions, choose the minimal
  # rectangular map of Earth that includes all points
  xlim <- c(min(the_divisions_to_plot$long),
            max(the_divisions_to_plot$long))
  ylim <- c(min(the_divisions_to_plot$lat),
            max(the_divisions_to_plot$lat))

  xlength <- diff(xlim)
  ylength <- diff(ylim)

  xlim <- c(xlim[1] - 0.025 * xlength - (city == "ADL") * xlength,
            xlim[2] + 0.025 * xlength)
  ylim <- c(ylim[1] - 0.025 * ylength,
            ylim[2] + 0.025 * ylength)

  pp <-
    the_divisions_to_plot %>%
    ggplot2::ggplot(.) +
    ggplot2::geom_polygon(ggplot2::aes_string(x = "long", 
                                              y = "lat", 
                                              fill = "fill",
                                              group = "group"),
                          color = polygon_outline_colour)

  if (coord_lines != "none"){
    if (grepl("lon", coord_lines, fixed = TRUE)){
      pp <-
        pp +
        ggplot2::geom_vline(xintercept = lon_lines) +
        ggplot2::annotate("label",
                 x = lon_lines,
                 label = as.character(lon_lines),
                 y = min(lat_lines) + 0.15 * (max(lat_lines) - min(lat_lines))) +
        ggplot2::annotate("label",
                 y = lat_lines,
                 x = min(lon_lines) + 0.15 * (max(lon_lines) - min(lon_lines)),
                 label = as.character(lat_lines))
    }

    if (grepl("lat", coord_lines, fixed = TRUE)){
      pp <-
        pp +
        ggplot2::geom_hline(yintercept = lat_lines) +
        ggplot2::annotate("label",
                          y = lat_lines,
                          x = min(lon_lines) + 0.15 * (max(lon_lines) - min(lon_lines)),
                          label = as.character(lat_lines))
    }
  }

  pp <-
    pp +
    ggplot2::coord_map(xlim = xlim, ylim = ylim) +
    ggthemes::theme_map(base_size = base_size,
                        base_family = base_family) +
    ggplot2::theme(legend.position = "none",
                   title = ggplot2::element_text(size = title.size),
                   plot.margin = ggplot2::margin())

  if (!is.null(scale_fill_manual_args)){
    pp <- pp + do.call(ggplot2::scale_fill_manual,
                       args = scale_fill_manual_args)
  }
  if (!is.null(scale_fill_gradientn_args)){
    pp <- pp + do.call(ggplot2::scale_fill_gradientn, 
                       args = scale_fill_gradientn_args)
  }

  if (title){
    the_title <- cities_abbrev[[city]]
    switch (city,
            "ADL" = {
              pp <- pp + ggplot2::annotate(geom = "text",
                                           label = "Adelaide",
                                           family = base_family,
                                           x = xlim[1],
                                           y = mean(ylim),
                                           size = 1.2*title.size / (14/5),
                                           hjust = 0)
            },
            "MEL" = {
              pp <-
                pp +
                ggplot2::ggtitle(the_title) +
                ggplot2::theme(plot.title = ggplot2::element_text(hjust = 0.5))
            },
            "PER" = {
              pp <-
                pp +
                ggplot2::ggtitle(the_title) +
                ggplot2::theme(plot.title = ggplot2::element_text(hjust = 0.5))
            },
            pp <- pp + ggplot2::ggtitle(the_title))
  }
  
  list(
    vwidth = city_inset_scale * xlength / lapply(aus_extent, diff)$xlim,
    vheight = city_inset_scale * ylength / lapply(aus_extent, diff)$ylim,
    p = pp)
}