ST_GridRing
Returns the hollow ring of H3 grids at exactly grid distance k from the origin grid. Unlike ST_GridDisk, which returns all grids within distance k, ST_GridRing returns only the grids on the outermost ring at that exact distance.
Syntax
SETOF h3grid ST_GridRing(h3grid origin, integer k)Parameters
| Parameter | Type | Description |
|---|---|---|
origin | h3grid | The central H3 grid. |
k | integer | The grid distance from the origin. |
Examples
The following example returns all H3 grids at grid distance 5 from the grid at latitude 25.1, longitude 123.1.
SELECT ST_GridRing(st_h3fromlatlng(25.1, 123.1), 5);Output:
st_griddisk
------------------------
01010060170363C5BAF408
01010066170363C5BAF408
01010062170363C5BAF408
01010063170363C5BAF408
01010061170363C5BAF408
....
(31 rows)What's next
ST_GridDisk: Returns all H3 grids within grid distancekfrom the origin (filled disk, not hollow ring).st_h3fromlatlng: Converts a latitude/longitude coordinate to an H3 grid value.