Add Greater Sydney boundary

NEWS.md

@@ -4,6 +4,7 @@
 * Fixed the `poa_nsw` dataset to avoid strange geometries near the state border.
 * Added geometries for Lord Howe Island, Australian Capital Territory, and
   Jervis Bay Territory, and a utility function `outline()` for using them.
+* Add Greater Sydney boundary as `sydney` dataset.
 * Slightly increase the resolution to 750 m instead of 1 km.
 * Update to the 2023 ASGS release, including the 2023 LGA shapefile.
 

R/data.R

@@ -49,7 +49,7 @@
 #'
 #' The geometry for `nsw` has been simplified with a tolerance of 750 m to
 #' reduce the level of detail, whereas the territories maintain their full
-#' resolution.
+#' resolution. `sydney` is simplified with a 500 m tolerance.
 #'
 #' @seealso [outline()]
 #' @source
@@ -65,6 +65,8 @@
 "lhi"
 #' @describeIn nsw Jervis Bay Territory boundary.
 "jbt"
+#' @describeIn nsw Greater Sydney boundary.
+"sydney"
 
 #' Geospatial data of the New South Wales administrative boundaries.
 #'

data-raw/.gitignore

@@ -7,4 +7,5 @@ MyHospitals_Public.zip
 MyHospitals_Public/
 confirmed_cases_table1_location_agg.csv
 STE_2021_AUST_SHP_GDA2020*
+GCCSA_2021_AUST_SHP_GDA2020*
 phn.geojson

data-raw/sydney.R

@@ -0,0 +1,35 @@
+gccsa_shapefile <- "data-raw/GCCSA_2021_AUST_SHP_GDA2020/GCCSA_2021_AUST_GDA2020.shp"
+
+if (!file.exists(abs_geopackage)) {
+  # https://www.abs.gov.au/statistics/standards/australian-statistical-geography-standard-asgs-edition-3
+  message("Downloading the source dataset from the ABS website...")
+  asgs_3e_url <- "https://www.abs.gov.au/statistics/standards/australian-statistical-geography-standard-asgs-edition-3/jul2021-jun2026/access-and-downloads/digital-boundary-files/GCCSA_2021_AUST_SHP_GDA2020.zip"
+  download.file(asgs_3e_url, destfile = "data-raw/GCCSA_2021_AUST_SHP_GDA2020.zip")
+
+  unzip("data-raw/GCCSA_2021_AUST_SHP_GDA2020.zip", exdir = "data-raw/GCCSA_2021_AUST_SHP_GDA2020")
+  stopifnot(file.exists(gccsa_shapefile))
+}
+
+library(sf)
+library(dplyr)
+library(nngeo)
+
+# reduce the resolution of the borders to 1km
+tolerance_m <- 500L
+
+crs_nsw <- sf::st_crs(7844) # GDA2020
+crs_working <- sf::st_crs("+proj=eqc +lat_ts=34 units=m")
+
+# st_layers(gccsa_shapefile)
+gccsa <- read_sf(gccsa_shapefile, layer = "GCCSA_2021_AUST_GDA2020")
+
+sydney_hires <- filter(gccsa, GCC_NAME21 == "Greater Sydney")
+sydney <- sydney_hires |>
+  st_transform(crs_working) |>
+  st_simplify(dTolerance = tolerance_m) |>
+  st_transform(crs_nsw) |>
+  st_geometry()
+object.size(sydney_hires)
+object.size(sydney)
+
+usethis::use_data(sydney, overwrite = TRUE)