Implement oe_get_boundary

First implementation of oe_get_bounday. Fix #206.

Some examples. First, load packages

library(osmextract)
#> Data (c) OpenStreetMap contributors, ODbL 1.0. https://www.openstreetmap.org/copyright.
#> Check the package website, https://docs.ropensci.org/osmextract/, for more details.
library(sf)
#> Linking to GEOS 3.10.2, GDAL 3.4.1, PROJ 7.2.1; sf_use_s2() is TRUE

Basic example

iow <- oe_get_boundary("Isle of Wight", quiet = TRUE)
plot(st_geometry(iow))

All administrative regions

oe_get_boundary("Isle of Wight", name = "%", exact = FALSE, quiet = TRUE)[, 1:3]
#> Simple feature collection with 34 features and 3 fields
#> Geometry type: MULTIPOLYGON
#> Dimension:     XY
#> Bounding box:  xmin: -1.591801 ymin: 50.57468 xmax: -1.062719 ymax: 50.76756
#> Geodetic CRS:  WGS 84
#> First 10 features:
#>    osm_id osm_way_id          name                       geometry
#> 1  154350       <NA> Isle of Wight MULTIPOLYGON (((-1.086357 5...
#> 2  214494       <NA>     Bembridge MULTIPOLYGON (((-1.101696 5...
#> 3  910850       <NA>     Calbourne MULTIPOLYGON (((-1.445158 5...
#> 4  910851       <NA>         Cowes MULTIPOLYGON (((-1.300432 5...
#> 5  910852       <NA>       Newport MULTIPOLYGON (((-1.25449 50...
#> 6  910859       <NA>       Brading MULTIPOLYGON (((-1.176043 5...
#> 7  910914       <NA>    Freshwater MULTIPOLYGON (((-1.53881 50...
#> 8  910917       <NA>      Yarmouth MULTIPOLYGON (((-1.50084 50...
#> 9  910918       <NA>     Shalfleet MULTIPOLYGON (((-1.445158 5...
#> 10 911503       <NA>      Shanklin MULTIPOLYGON (((-1.213082 5...

Unfortunately, this does not always work

oe_get_boundary("Leeds", quiet = TRUE)
#> Simple feature collection with 0 features and 25 fields
#> Bounding box:  xmin: NA ymin: NA xmax: NA ymax: NA
#> Geodetic CRS:  WGS 84
#>  [1] osm_id      osm_way_id  name        type        aeroway     amenity    
#>  [7] admin_level barrier     boundary    building    craft       geological 
#> [13] historic    land_area   landuse     leisure     man_made    military   
#> [19] natural     office      place       shop        sport       tourism    
#> [25] other_tags  geometry   
#> <0 rows> (or 0-length row.names)

We may need slightly different approaches

leeds <- oe_get_boundary("West Yorkshire", "Leeds", quiet = TRUE)
plot(st_geometry(leeds))

^{Created on 2022-08-17 by the reprex package (v2.0.1)}

ropensci / osmextract

Implement oe_get_boundary #263