Transform list items to property – JSONLD

I want to extract RDF from an API and I use jsonld with javascript to do it. The json from the API look like this :

  "datasetid": "etat-des-stations-le-velo-star-en-temps-reel",
  "recordid": "88a8871cd455b991aae541e2d60ebdab34840e3e",
  "fields": {
    "etat": "En fonctionnement",
    "lastupdate": "2021-03-19T17:33:18+00:00",
    "nombrevelosdisponibles": 6,
    "nombreemplacementsactuels": 16,
    "nom": "Musée Beaux-Arts",
    "nombreemplacementsdisponibles": 10,
    "idstation": "5510",
    "coordonnees": [
      48.109601,
      -1.67408
    ]
  },
  "geometry": {
    "type": "Point",
    "coordinates": [
      -1.67408,
      48.109601
    ]
  },
  "record_timestamp": "2021-03-19T17:33:00+00:00"
}

and I have defined this context:

const context_bike = {
"@vocab": "http://schema.org/",
"@base": "http://data.org/",
"geometry":null,
"datasetid":null,
"recordid":null,
"record_timestamp":null,
"field": "@nest",
"idstation": "@id",
"coordonnees":"???",
"nombreemplacementsdisponibles":{"@id":"AvailableSpaceNumber", "@type":"xsd:integer"},
"nom": {"@id":"name", "@type":"xsd:string"},
"nombrevelosdisponibles": {"@id":"AvailableBikeNumber", "@type":"xsd:integer"},
"lastupdate":{"@id":"lastupdate", "@type":"xsd:dateTime"},
"state":{"@id":"etat", "@type":"xsd:string"}

}

I just have a problem to extract data from “coordonnees”. I would like to have a property lat and another long which correspond to the first and second element of the “coordonnees” array.

How can I do this ? And I also see in other example the definition of the word “@context”, do i have to add it ? I juste added “@vocab” and when i add “@context” it create weird n triple and even the null properties are defined.

Thanks!

Answer

You probably want to have a look at Geo JSON-LD (http://geojson.org/geojson-ld/) for describing coordinates using lists. You could then use SPARQL (or GeoSPARQL) to get lat/long into properties.