Visualise sf objects with insets

These geoms are wrappers around ggplot2::geom_sf() and its relatives that assist with creating map insets. In many cases all that is needed is to use coord_sf_inset() with configure_inset() to configure the location and transformation of the inset, and then replace the sf-related geoms with their _inset counterparts. Use geom_inset_frame() to add a frame around the inset that connects it to the main map.

Usage

geom_sf_inset(
  mapping = ggplot2::aes(),
  data = NULL,
  stat = "sf_inset",
  position = "identity",
  ...,
  inset = NA,
  map_base = "normal",
  map_inset = "auto",
  na.rm = TRUE,
  show.legend = NA,
  inherit.aes = TRUE
)

stat_sf_inset(
  mapping = ggplot2::aes(),
  data = NULL,
  geom = "sf_inset",
  position = "identity",
  ...,
  inset = NA,
  na.rm = TRUE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping, data, stat, geom, position, na.rm, show.legend, inherit.aes, ...

See ggplot2::geom_sf().

inset

Inset configuration; see configure_inset(). If NA (the default), this is inherited from the coord (see coord_sf_inset()).

map_base

Controls the layer with the base map. Possible values are "normal" to create a layer as though the inset were not specified, "clip" to create a layer with the inset viewport cut out, and "none" to prevent the insertion of a layer for the base map.

map_inset

Controls the layer with the inset map. Possible values are "auto" to choose the behaviour based on whether inset is specified, "normal" to create a layer with the viewport cut out and transformed, and "none" to prevent the insertion of a layer for the viewport map.

Value

A ggplot layer similar to ggplot2::geom_sf() but transformed according to the inset configuration.

Details

Internally this works by creating two layers: one for the base map, and one for the inset. These can be separately controlled by the map_base and map_inset parameters. If inset is not specified, this geom will instead behave like ggplot2::geom_sf().

When an inset is configured, the default creates both base and inset layers using the same aesthetic mapping and params:

geom_sf_inset(...)

You can alternatively specify the two layers separately:

# draw the base map only (both versions are equivalent):
geom_sf(...)
geom_sf_inset(..., map_inset = "none")

# separately, draw the inset map only:
geom_sf_inset(..., map_base = "none")

stat_sf_inset() works the same ggplot2::stat_sf() except that it also expands the axis limits to account for the inset area.

Examples

library(ggplot2)

nc <- sf::st_read(system.file("shape/nc.shp", package = "sf"), quiet = TRUE)

ggplot(nc) +
  geom_sf_inset(aes(fill = AREA)) +
  geom_inset_frame() +
  coord_sf_inset(configure_inset(
    shape_circle(
      centre = sf::st_sfc(sf::st_point(c(-80, 35.5)), crs = sf::st_crs(nc)),
      radius = 50
    ),
    scale = 1.5, translation = c(-50, -140), units = "mi"
  ))