Check if a given CRS is in meters or degrees.

Check if a given CRS is in meters or degrees.

Usage

check_crs_units(crs_input)

Arguments

crs_input

The CRS, which can be an EPSG code, WKT string, or PROJ.4 string.

Value

"km" if it's in meters, "degrees" if it's in degrees. Otherwise, throws an informative error.

Examples

tryCatch({
  print(check_crs_units(4326)) # EPSG:4326 (degrees)
  print(check_crs_units(25832)) # EPSG:25832 (meters)
  print(check_crs_units("+proj=longlat +datum=WGS84 +no_defs")) # PROJ.4 (degrees)
  print(check_crs_units("+proj=utm +zone=32 +datum=WGS84 +units=m +no_defs")) # PROJ.4 (meters)
  print(check_crs_units("+proj=somerc +lat_0=0 +lon_0=0 +k=1 +x_0=0 +y_0=0
        +ellps=WGS84 +units=km +no_defs")) # Invalid CRS
  print(check_crs_units("not a crs")) # Invalid CRS
  print(check_crs_units("+proj=lcc +lat_1=33 +lat_2=45 +lat_0=39 +lon_0=-96
        +x_0=0 +y_0=0 +datum=NAD83 +units=us-ft +no_defs")) # Invalid units
}, error = function(e) {
  print(e$message)
})
#> [1] "could not find function \"check_crs_units\""