Check CRS of a table

Usage

ddbs_crs(conn, name, crs_column = "crs_duckspatial")

Arguments

conn: a connection object to a DuckDB database
name: a character string of length one specifying the name of the table, or a character string of length two specifying the schema and table names.
crs_column: a character string of length one specifying the column storing the CRS (created automatically by ddbs_write_vector)

Value

CRS object

Examples

# \donttest{
## load packages
library(duckdb)
library(duckspatial)
library(sf)
#> Linking to GEOS 3.12.1, GDAL 3.8.4, PROJ 9.4.0; sf_use_s2() is TRUE

## database setup
conn <- dbConnect(duckdb())
ddbs_install(conn)
#> ✔ Spatial extension installed
ddbs_load(conn)
#> ✔ Spatial extension loaded

## read data
countries_sf <- st_read(system.file("spatial/countries.geojson", package = "duckspatial"))
#> Reading layer `countries' from data source 
#>   `/home/runner/work/_temp/Library/duckspatial/spatial/countries.geojson' 
#>   using driver `GeoJSON'
#> Simple feature collection with 257 features and 6 fields
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: -178.9125 ymin: -89.9 xmax: 180 ymax: 83.65187
#> Geodetic CRS:  WGS 84

## store in duckdb
ddbs_write_vector(conn, countries_sf, "countries")
#> ✔ Table countries successfully imported

## check CRS
ddbs_crs(conn, "countries")
#> Coordinate Reference System:
#>   User input: EPSG:4326 
#>   wkt:
#> GEOGCRS["WGS 84",
#>     ENSEMBLE["World Geodetic System 1984 ensemble",
#>         MEMBER["World Geodetic System 1984 (Transit)"],
#>         MEMBER["World Geodetic System 1984 (G730)"],
#>         MEMBER["World Geodetic System 1984 (G873)"],
#>         MEMBER["World Geodetic System 1984 (G1150)"],
#>         MEMBER["World Geodetic System 1984 (G1674)"],
#>         MEMBER["World Geodetic System 1984 (G1762)"],
#>         MEMBER["World Geodetic System 1984 (G2139)"],
#>         ELLIPSOID["WGS 84",6378137,298.257223563,
#>             LENGTHUNIT["metre",1]],
#>         ENSEMBLEACCURACY[2.0]],
#>     PRIMEM["Greenwich",0,
#>         ANGLEUNIT["degree",0.0174532925199433]],
#>     CS[ellipsoidal,2],
#>         AXIS["geodetic latitude (Lat)",north,
#>             ORDER[1],
#>             ANGLEUNIT["degree",0.0174532925199433]],
#>         AXIS["geodetic longitude (Lon)",east,
#>             ORDER[2],
#>             ANGLEUNIT["degree",0.0174532925199433]],
#>     USAGE[
#>         SCOPE["Horizontal component of 3D system."],
#>         AREA["World."],
#>         BBOX[-90,-180,90,180]],
#>     ID["EPSG",4326]]
# }