This is a quick and dirty way to get map data (from the maps package) onto 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.
Usage
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 thesubgroup
aesthetic) this argument defines how the hole coordinates are interpreted. See the examples ingrid::pathGrob()
for an explanation.mapping
Set of aesthetic mappings created by
aes()
. If specified andinherit.aes = TRUE
(the default), it is combined with the default mapping at the top level of the plot. You must supplymapping
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 toggplot()
.A
data.frame
, or other object, will override the plot data. All objects will be fortified to produce a data frame. Seefortify()
for which variables will be created.A
function
will be called with a single argument, the plot data. The return value must be adata.frame
, and will be used as the layer data. Afunction
can be created from aformula
(e.g.~ head(.x, 10)
).stat
The statistical transformation to use on the data for this layer, either as a
ggproto
Geom
subclass or as a string naming the stat stripped of thestat_
prefix (e.g."count"
rather than"stat_count"
)position
Position adjustment, either as a string naming the adjustment (e.g.
"jitter"
to useposition_jitter
), or the result of a call to a position adjustment function. Use the latter if you need to change the settings of the adjustment.show.legend
logical. Should this layer be included in the legends?
NA
, the default, includes if any aesthetics are mapped.FALSE
never includes, andTRUE
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. IfTRUE
, 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
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()
}
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()
}