How do you convert a dictionary with objects into geoJson?

Question

We have a dictionary with cities, using a uniqe id as the key:

cities: {
    'adfjlx9w': {
      name: 'New York',
      latitude: 4,
      longitude: -7
    },
    'favkljsl9': {
      name: 'Copenhagen',
      latitude: 2,
      longitude: -18
    }
  }

We need to convert our dictionary into Geojson in order to place the cities on a map, but cannot use the typical route below, as it is not an array of objects:

GeoJSON.parse(cities, {
      Point: ['latitude', 'longitude']
    });

What is the fastest and best way to do this?

Answer 1

If I understand correctly, you need to extract the latitude and longitude data for each value of the cities object to an array of latitude/longitude values of shape:

{ latitude, longitude }

One approach would be to use Object#values which returns an array of the values for cities , and, optional use Array#map to transform each object to a new object (with only the latitude, longitude values):

 const cities = { 'adfjlx9w': { name: 'New York', latitude: 4, longitude: -7 }, 'favkljsl9': { name: 'Copenhagen', latitude: 2, longitude: -18 } } const latlngArray = Object // Extract value array from cities .values(cities) // Map each value to lat/lng only object .map(item => ({ latitude : item.latitude, longitude : item.longitude })) console.log(latlngArray); /* Pass latlngArray to GeoJSON.parse GeoJSON.parse(latlngArray, { Point: ['latitude', 'longitude'] }); */

Hope that helps!

Answer 2

Something like this should work.

const citiesArray = Object.values(cities);

GeoJSON.parse(citiesArray, {
      Point: ['latitude', 'longitude']
    });

Answer 3

According to the GeoJSON Specification, to include the id and name properties with latitude/longitude coordinates, you would need to parse the object as type FeatureCollection with a property features .

Each features array object should be of type Feature , with properties and geometry values. The properties value should contain the metadata, and the geometry value should be of type Point with coordinates property containing latitude/longitude.

const cities = {
  'adfjlx9w': {
    name: 'New York',
    latitude: 4,
    longitude: -7
  },
  'favkljsl9': {
    name: 'Copenhagen',
    latitude: 2,
    longitude: -18
  }
}

let citiesGeoJSON = Object.entries(cities)
  .reduce((
    _cities,
    [cityID, cityData],
  ) => {
    let city = {
      "type": "Feature",
      "properties": {
        "id": cityID,
        "name": cityData.name,
      },
      "geometry": {
        "type": 'Point',
        "coordinates": [
          cityData.latitude,
          cityData.longitude,
        ],
      },
    }
    _cities.features.push(city)
    return _cities
  }, {
    "type": "FeatureCollection",
    "features": [],
  })

There is a GeoJSON Linter online.