(topology) some geometry has no arcs and no known use

[ryanparker-st]

Some maps have geometries that do not have any known use. They only have a single arc with value 0 and their hc-keys do not match any known geographical code.

Examples:

mx-all.topo.json (Mexico)

{
          "type": "Polygon",
          "arcs": [
            [
              0
            ]
          ],
          "id": "MX.3622",
          "properties": {
            "hc-group": "admin1",
            "hc-key": "mx-3622",
            "hc-a2": "NU",
            "labelrank": "20",
            "hasc": "-99",
            "alt-name": null,
            "woe-id": "-99",
            "subregion": null,
            "fips": null,
            "postal-code": null,
            "name": null,
            "country": "Mexico",
            "type-en": null,
            "region": null,
            "longitude": "-89.66330000000001",
            "woe-name": null,
            "latitude": "22.3858",
            "woe-label": null,
            "type": null,
            "hc-middle-lon": -89.653,
            "hc-middle-lat": 22.472
          }
        }

ca-all.topo.json (Canada)

{
          "type": "Polygon",
          "arcs": [
            [
              0
            ]
          ],
          "id": "CA.5682",
          "properties": {
            "hc-group": "admin1",
            "hc-key": "ca-5682",
            "hc-a2": "NU",
            "labelrank": "20",
            "hasc": "-99",
            "alt-name": null,
            "woe-id": "-99",
            "subregion": null,
            "fips": null,
            "postal-code": null,
            "name": null,
            "country": "Canada",
            "type-en": null,
            "region": null,
            "longitude": "-61.4664",
            "woe-name": null,
            "latitude": "47.7941",
            "woe-label": null,
            "type": null,
            "hc-middle-lon": -61.466,
            "hc-middle-lat": 47.793
          }
        }

[hubertkozik]

Hi @ryanparker-st! Thanks for reporting this issue. We're currently in the process of generating new maps from a new source, so cases like the one you found will be resolved in future updates. In the meantime, as a workaround, you can modify the TopoJSON yourself and remove any objects with unknown geometry. Let us know if you need any help!

[KacperMadej]

They only have a single arc with value 0

Each geometry have arc index(es) and the actual arc can be found next to the geometries in arcs property. Index number doesn't reflect the arc size. Geometries with a single arc are unique paths that do not share border with any other geometry - usually a separated island (or the whole geometry is there's only 1 in the TopoJSON).

For Mexico, MX.3622 comes from the Natural Earth map source and is this "island"(?) - link.

For Canada, very similar situation, this is ca-5682 and comes from the Natural Earth map source.

If you don't need it you can not use it. If you are looking for help with how to (not) use this please contact technical support. When the maps will be update these problems will be resolved, so I would like to close this issue as an answered question. Will this be ok @ryanparker-st ?