ll_bbox: Provide a bounding box with a consistent, user given ratio

In giocomai/latlon2map: Facilitates matching lat/lon data with administrative units and other geographic shapes

Provide a bounding box with a consistent, user given ratio

Description

This is useful in particular to make geom_sf()-based ggplots with consistent aspect ratio.

Usage

ll_bbox(sf, ratio = "4:3")

Arguments

sf	An sf object.
ratio	Defaults to "4:3". A chacters string, in the form of e.g. "4:3" or "16:9" or "1:1" (other values possible)

Value

A bounding box vector, same as with sf::st_bbox(), but with the given ratio set and compatible with crs 4326.

Examples

## Not run: 
# The following two graphs will have same 4:3 aspect ratio
ll_set_folder("~/R/")
library("ggspatial")

sf_location <- ll_get_nuts_it(name = "Palmanova", level = "lau", resolution = "low")

ggplot() +
  annotation_map_tile(type = "osm", zoomin = -1, cachedir = fs::path(ll_set_folder(), "ll_data")) +
  geom_sf(data = sf::st_as_sfc(ll_bbox(sf_location)), fill = NA, color = NA) +
  geom_sf(
    data = sf_location,
    colour = "darkred",
    size = 2,
    fill = NA,
    alpha = 0.8
  )


sf_location <- ll_get_nuts_it(name = "Pinzolo", level = "lau", resolution = "low")

ggplot() +
  annotation_map_tile(type = "osm", zoomin = -1, cachedir = fs::path(ll_set_folder(), "ll_data")) +
  geom_sf(data = sf::st_as_sfc(ll_bbox(sf_location)), fill = NA, color = NA) +
  geom_sf(
    data = sf_location,
    colour = "darkred",
    size = 2,
    fill = NA,
    alpha = 0.8
  )

## End(Not run)

giocomai/latlon2map documentation built on Aug. 4, 2023, 2:12 p.m.