title: Calling geojson_list in R
body: <p>I have a csv file with the locations of bicicle stations in four columns: "long", "lat", "nro_est", "nombre". I want to create a geojson fil from this csv file doing this:</p>
  
  <pre><code>as.json(geojson_list(estaciones, lat = 'lat', long = 'long'), pretty = TRUE)
  </code></pre>
  
  <p>the example from <code>?geojson_list</code> with data "states" is very similar but instead of creating points it creates polygons:</p>
  
  <pre><code>geojson_list(states[1:351,], geometry="polygon", group='group')
  </code></pre>
  
  <p>My problem with my adaption brings this error. It takes "nro_est" and "nombre" as coordinates and also it shows "long" as propertie. There is an NA that i dont understand. What am i doing wrong?</p>
  
  <pre><code>   "geometry": {
          "type": "Point",
          "coordinates": [-58.40436, -34.58819, 200, "NA"]
        },
     "properties": {
          "long": "-58.40436",
          "nro_est": "200",
          "nombre": "Austria y French"
        }
  </code></pre>