R/geom_africa_tilemap.R

In delabj/AfricaCountryBins: Create a countrybin map of Africa

#' A tilemap of Africa
#'
#' @description
#' Based off the work of \href{https://github.com/hrbrmstr/statebins}{Bob Rudis's Statebins} this package aims to create a workable tile map of Africa for ggplot2.
#' Simply pass in a dataframe containing countries and values to measure, and this geom will create a simple map. This allows for easy faceting and allows a uniform legend across all plots.
#'
#' Much like the origional statebins package, there are two critical `aes()` mappings: \cr
#' - `country` (so the geom knows which column to map the country names/abbreviations to)
#' - `fill` (the column you're mapping the filling with.)
#'
#' @md
#' @param mapping Set of aesthetic mappings created by `aes()` or
#'   `aes_()`. If specified and `inherit.aes = TRUE` (the
#'   default), it is combined with the default mapping at the top level of the
#'   plot. You must supply `mapping` if there is no plot mapping.
#' @param data The data to be displayed in this layer. There are three
#'    options:
#'
#'    If `NULL`, the default, the data is inherited from the plot
#'    data as specified in the call to `ggplot()`.
#'
#'    A `data.frame`, or other object, will override the plot
#'    data. All objects will be fortified to produce a data frame. See
#'    `fortify()` for which variables will be created.
#'
#'    A `function` will be called with a single argument,
#'    the plot data. The return value must be a `data.frame.`, and
#'    will be used as the layer data.
#' @param border_col border color of the country squares, default "`white`"
#' @param border_size thickness of the square country borders
#' @param lbl_size font size (relative) of the label text
#' @param dark_lbl,light_lbl colrs to be uses when the label should be dark or light.
#'        The function automagically computes when this should be.
#' @param radius the corner radius
#' @param na.rm If `FALSE`, the default, missing values are removed with
#'   a warning. If `TRUE`, missing values are silently removed.
#' @param ... other arguments passed on to `layer()`. These are
#'   often aesthetics, used to set an aesthetic to a fixed value, like
#'   `color = "red"` or `size = 3`. They may also be parameters
#'   to the paired geom/stat.
#' @param show.legend logical. Should this layer be included in the legends?
#'   `NA`, the default, includes if any aesthetics are mapped.
#'   `FALSE` never includes, and `TRUE` always includes.
#'   It can also be a named logical vector to finely select the aesthetics to
#'   display.
#' @param inherit.aes If `FALSE`, overrides the default aesthetics,
#'   rather than combining with them. This is most useful for helper functions
#'   that define both data and aesthetics and shouldn't inherit behaviour from
#'   the default plot specification, e.g. `borders()`.
#' @export
geom_africa_tilemap <- function(
                         mapping = NULL,
                         data = NULL,
                         border_col = "white",
                         border_size = 2,
                         lbl_size = 3,
                         dark_lbl = "black",
                         light_lbl = "white",
                         radius = grid::unit(6, "pt"),
                         ...,
                         na.rm=FALSE,
                         show.legend = NA,
                         inherit.aes = TRUE
                         ){
  ggplot2::layer(
    data = data,
    mapping = mapping,
    stat = "identity",
    geom = GeomAfricaTileMap,
    position = "identity",
    show.legend = show.legend,
    inherit.aes = inherit.aes,
    params = list(
      border_col = border_col,
      border_size = border_size,
      lbl_size = lbl_size,
      dark_lbl = dark_lbl,
      light_lbl = light_lbl,
      radius = radius,
      na.rm = na.rm,
      ...
    )
  )
  }


#' @rdname geom_africa_tilemap
#' @export
GeomAfricaTileMap <- ggplot2::ggproto(
  "GeomAfricaTileMap",
  ggplot2::Geom,
  default_aes = ggplot2::aes(
    fill       = "grey20",
    colour     = NA,
    size       = 0.1,
    linetype   = 1,
    country    = "country",
    label      = "abrv_3_letter",
    angle      = 0,
    hjust      = 0.5,
    vjust      = 0.5,
    family     = "",
    fontface   = 1,
    lineheight = 1.2
  ),
  extra_params = c(
    "na.rm",
    "width",
    "height"
    ),
  setup_data = function(data, params){

    country_data <- data.frame(data, stringsAsFactors = FALSE)

    if(max(nchar(country_data[,"country"])) <= 2 ){
      merge.x <- "abrv_2_letter"
    }
    else if(max(nchar(country_data[,"country"])) <= 3 ){
      merge.x <- "abrv_3_letter"

    }
    else {
      merge.x <- "country"
    }


    country_data <- validate_countries(
      country_data,
      "country",
      merge.x,
      ignore_dupes = TRUE)

    cntry.dat <- merge(
      b_country_coords,
      country_data,
      by.x = merge.x,
      by.y = "country",
      all.y = TRUE,
      sort = TRUE
    )
    cntry.dat$width  <- cntry.dat$width  %||% params$width  %||% ggplot2::resolution(cntry.dat$x, FALSE)
    cntry.dat$height <- cntry.dat$height %||% params$height %||% ggplot2::resolution(cntry.dat$y, FALSE)

    xdat <- transform(
      cntry.dat,
      xmin   = x - width / 2,
      xmax   = x + width / 2,
      width  = NULL,
      ymin   = y - height / 2,
      ymax   = y + height / 2,
      height = NULL
    )

    xdat

  },

  required_aes = c(
    "country",
    "fill"
  ),

  draw_panel = function(
    self,
    data,
    panel_params,
    coord,
    border_col = "white",
    border_size = 2,
    lbl_size = 3,
    dark_lbl = "black",
    light_lbl = "white",
    radius = grid::unit(6, "pt")
  ){

    tile_data        <- data
    tile_data$size   <- border_size
    tile_data$colour <- border_col

    text_data <-  data
    text_data$label <- data$abrv_3_letter
    text_data$fill <- NA
    text_data$size <-  lbl_size
    text_data$colour <- .sb_invert(data$fill, dark_lbl, light_lbl)

    coord <- coord_equal()

    grid::gList(
      GeomRtile$draw_panel(tile_data, panel_params, coord, radius),
      ggplot2::GeomText$draw_panel(text_data, panel_params, coord)
    ) -> grobs

    ggname("geom_africa_tilemap", grid::grobTree(children = grobs))
  },

  draw_key = ggplot2::draw_key_polygon



  )