This function can be used to obtain polygon/multipolygon objects representing
an administrative boundary. The objects are extracted from the
multipolygons layer of a given OSM extract.
oe_get_boundary(place, name = place, exact = TRUE, ...)Description of the geographical area that should be matched with
a .osm.pbf file. Can be either a length-1 character vector, an
sf/sfc/bbox object with any CRS, or a numeric vector of coordinates
with length 2. In the last case, it is assumed that the EPSG code is 4326
specified as c(LON, LAT), while you can use any CRS with sf/sfc/bbox
objects. See Details and Examples in oe_match().
A character vector of length 1 that describes the relevant area.
By default, this is equal to place, but this parameter can be tuned to
obtain more granular results starting from the same OSM extract. See
examples. It must be always set when the place argument is specified
using numeric or spatial objects.
Boolean of length 1. If TRUE, then the function returns only
those features where the field name is exactly equal to name. If
FALSE, it performs a (case-sensitive) pattern matching.
Further arguments (e.g. quiet or force_vectortranslate) that
are passed to oe_get().
An sf object
The function may return an empty result when the corresponding GPKG file
already exists and contains partial results. In that case, you can try
running the function setting never_skip_vectortranslate = TRUE.
if (FALSE) { # \dontrun{
library(sf)
my_cols = sf.colors(5, categorical = TRUE)
gabon = oe_get_boundary("Gabon", quiet = TRUE) # country
libreville = oe_get_boundary("Gabon", "Libreville", quiet = TRUE) # capital
opar = par(mar = rep(0, 4))
plot(st_geometry(st_boundary(gabon)), reset = FALSE, col = "grey")
plot(st_geometry(libreville), add = TRUE, col = my_cols[1])
# Exact match
komo = oe_get_boundary("Gabon", "Komo", quiet = TRUE)
# Pattern matching
komo_pt = oe_get_boundary("Gabon", "Komo", exact = FALSE, quiet = TRUE)
plot(st_geometry(komo), add = TRUE, col = my_cols[2])
plot(st_geometry(komo_pt), add = TRUE, col = my_cols[3:5])
par(opar)
# Get all boundaries
(oe_get_boundary("Gabon", name = "%", exact = FALSE, quiet = TRUE)[, 1:2])
# If the basic approach doesn't work, i.e.
oe_get_boundary("Leeds")
# try to consider larger regions, i.e.
oe_get_boundary("West Yorkshire", "Leeds")
} # }