GeoJSON Transform
The geojson transform consolidates geographic data into a single GeoJSON feature collection. The generated GeoJSON data can then be used to parameterize other parts of a Vega specification, namely the projection fit parameter. This transform can process both latitude / longitude data and existing GeoJSON features.
Transform Parameters
| Property | Type | Description |
|---|---|---|
| fields | Field[ ] | Data fields containing longitude and latitude values, respectively. |
| geojson | Field | Data field containing GeoJSON Feature objects. For Vega versions ≥ 5.7, this parameter defaults to the identity function (treat input data objects as GeoJSON Feature objects) if neither this parameter nor the fields parameter are specified. |
Usage
In the midst of a data transform array, one can include a geojson transform and bind it to a new signal name (here, geodata):
{
"type": "geojson",
"fields": ["longitude", "latitude"],
"signal": "geodata"
}
Elsewhere, the geodata signal can be used to refer to the consolidated GeoJSON data, as in a projection:
"projections": [
{
"name": "proj",
"type": "mercator",
"fit": {"signal": "geodata"}
}
]