Create a layer of map borders

This is a quick and dirty way to get map data (from the maps package) on to your plot. This is a good place to start if you need some crude reference lines, but you'll typically want something more sophisticated for communication graphics.

borders(database = "world", regions = ".", fill = NA,
  colour = "grey50", xlim = NULL, ylim = NULL, ...)

Arguments

database	map data, see `maps::map()` for details
regions	map region
fill	fill colour
colour	border colour
xlim, ylim	latitudinal and longitudinal ranges for extracting map polygons, see `maps::map()` for details.
...	Arguments passed on to `geom_polygon` rule Either `"evenodd"` or `"winding"`. If polygons with holes are being drawn (using the `subgroup` aesthetic) this argument defines how the hole coordinates are interpreted. See the examples in `grid::pathGrob()` for an explanation. 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. 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. A `function` can be created from a `formula` (e.g. `~ head(.x, 10)`). stat The statistical transformation to use on the data for this layer, as a string. position Position adjustment, either as a string, or the result of a call to a position adjustment function. 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. 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()`. na.rm If `FALSE`, the default, missing values are removed with a warning. If `TRUE`, missing values are silently removed.

Examples

if (require("maps")) {

ia <- map_data("county", "iowa")
mid_range <- function(x) mean(range(x))
seats <- do.call(rbind, lapply(split(ia, ia$subregion), function(d) {
  data.frame(lat = mid_range(d$lat), long = mid_range(d$long), subregion = unique(d$subregion))
}))

ggplot(ia, aes(long, lat)) +
  geom_polygon(aes(group = group), fill = NA, colour = "grey60") +
  geom_text(aes(label = subregion), data = seats, size = 2, angle = 45)
}
#> Loading required package: maps
#> Warning: there is no package called ‘maps’

if (require("maps")) {
data(us.cities)
capitals <- subset(us.cities, capital == 2)
ggplot(capitals, aes(long, lat)) +
  borders("state") +
  geom_point(aes(size = pop)) +
  scale_size_area() +
  coord_quickmap()
}
#> Loading required package: maps
#> Warning: there is no package called ‘maps’

if (require("maps")) {
# Same map, with some world context
ggplot(capitals, aes(long, lat)) +
  borders("world", xlim = c(-130, -60), ylim = c(20, 50)) +
  geom_point(aes(size = pop)) +
  scale_size_area() +
  coord_quickmap()
}
#> Loading required package: maps
#> Warning: there is no package called ‘maps’

Arguments

Examples

Contents