Add or get CRS

Add or get CRS

Usage

crs_add(x, crs)

crs_get(x)

Arguments

x

An object of class geojson

crs

(character) a CRS string. required.

Details

According to RFC 7946 (https://datatracker.ietf.org/doc/html/rfc7946#page-12) the CRS for all GeoJSON objects must be WGS-84, equivalent to urn:ogc:def:crs:OGC::CRS84. And lat/long must be in decimal degrees.

Given the above, but considering that GeoJSON blobs exist that have CRS attributes in them, we provide CRS helpers here. But moving forward these are not likely to be used much.

References

https://github.com/OSGeo/PROJ, https://geojson.org/geojson-spec.html#coordinate-reference-system-objects

Examples

x <- '{ "type": "Polygon",
"coordinates": [
  [ [100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0], [100.0, 0.0] ]
  ]
}'

# add crs
crs <- '{"type": "name",
 "properties": {
     "name": "urn:ogc:def:crs:OGC:1.3:CRS84"
}}'
x %>% feature() %>% crs_add(crs)
#> {
#>     "type": "Feature",
#>     "properties": {
#> 
#>     },
#>     "geometry": {
#>         "type": "Polygon",
#>         "coordinates": [
#>             [
#>                 [
#>                     100.0,
#>                     0.0
#>                 ],
#>                 [
#>                     101.0,
#>                     0.0
#>                 ],
#>                 [
#>                     101.0,
#>                     1.0
#>                 ],
#>                 [
#>                     100.0,
#>                     1.0
#>                 ],
#>                 [
#>                     100.0,
#>                     0.0
#>                 ]
#>             ]
#>         ]
#>     },
#>     "crs": {
#>         "type": "name",
#>         "properties": {
#>             "name": "urn:ogc:def:crs:OGC:1.3:CRS84"
#>         }
#>     }
#> }

# get crs
z <- x %>% feature() %>% crs_add(crs)
crs_get(z)
#> $type
#> [1] "name"
#> 
#> $properties
#> $properties$name
#> [1] "urn:ogc:def:crs:OGC:1.3:CRS84"
#> 
#>