geo_s2cell_neighbors()

  • Article
  • 09/11/2024

Applies to: ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel

Calculates S2 cell neighbors.

Read more about S2 cell hierarchy.

Syntax

geo_s2cell_neighbors(s2cell)

Learn more about syntax conventions.

Parameters

Name Type Required Description
s2cell string ✔️ S2 cell token value as it was calculated by geo_point_to_s2cell(). The S2 cell token maximum string length is 16 characters.

Returns

An array of S2 cell neighbors. If the S2 Cell is invalid, the query produces a null result.

Note

S2 Cell edges are spherical geodesics.

Examples

The following example calculates S2 cell neighbors.

Run the query

print neighbors = geo_s2cell_neighbors('89c259')

Output

neighbors
["89c25d","89c2f9","89c251","89c257","89c25f","89c25b","89c2f7","89c2f5"]

The following example calculates an array of input S2 cell with its neighbors.

Run the query

let s2cell = '89c259';
print cells = array_concat(pack_array(s2cell), geo_s2cell_neighbors(s2cell))

Output

cells
["89c259","89c25d","89c2f9","89c251","89c257","89c25f","89c25b","89c2f7","89c2f5"]

The following example calculates S2 cells polygons GeoJSON geometry collection.

Run the query

let s2cell = '89c259';
print cells = array_concat(pack_array(s2cell), geo_s2cell_neighbors(s2cell))
| mv-expand cells to typeof(string)
| project polygons = geo_s2cell_to_polygon(cells)
| summarize arr = make_list(polygons)
| project geojson = bag_pack("type", "Feature","geometry", bag_pack("type", "GeometryCollection", "geometries", arr), "properties", bag_pack("name", "polygons"))

Output

geojson
{"type": "Feature","geometry": {"type": "GeometryCollection","geometries": [
{"type": "Polygon","coordinates": [[[ -74.030012249838478, 40.8012684339439],[ -74.030012249838478, 40.7222262918358],[ -73.935982114337421, 40.708880489804564],[ -73.935982114337421, 40.787917134506841],[ -74.030012249838478, 40.8012684339439]]]},
{"type": "Polygon","coordinates": [[[ -73.935982114337421, 40.708880489804564],[ -73.935982114337421, 40.629736433321796],[ -73.841906340776248, 40.616308079144915],[ -73.841906340776248, 40.695446474556284],[ -73.935982114337421, 40.708880489804564]]]},
{"type": "Polygon","coordinates": [[[ -74.1239959854733, 40.893471289549765],[ -74.1239959854733, 40.814531536204242],[ -74.030012249838478, 40.8012684339439],[ -74.030012249838478, 40.880202851376716],[ -74.1239959854733, 40.893471289549765]]]},
{"type": "Polygon","coordinates": [[[ -74.1239959854733, 40.735483949993387],[ -74.1239959854733, 40.656328734184143],[ -74.030012249838478, 40.643076628676461],[ -74.030012249838478, 40.7222262918358],[ -74.1239959854733, 40.735483949993387]]]},
{"type": "Polygon","coordinates": [[[ -74.1239959854733, 40.814531536204242],[ -74.1239959854733, 40.735483949993387],[ -74.030012249838478, 40.7222262918358],[ -74.030012249838478, 40.8012684339439],[ -74.1239959854733, 40.814531536204242]]]},
{"type": "Polygon","coordinates": [[[ -73.935982114337421, 40.787917134506841],[ -73.935982114337421, 40.708880489804564],[ -73.841906340776248, 40.695446474556284],[ -73.841906340776248, 40.774477568182071],[ -73.935982114337421, 40.787917134506841]]]},
{"type": "Polygon","coordinates": [[[ -74.030012249838478, 40.7222262918358],[ -74.030012249838478, 40.643076628676461],[ -73.935982114337421, 40.629736433321796],[ -73.935982114337421, 40.708880489804564],[ -74.030012249838478, 40.7222262918358]]]},
{"type": "Polygon","coordinates": [[[ -74.030012249838478, 40.880202851376716],[ -74.030012249838478, 40.8012684339439],[ -73.935982114337421, 40.787917134506841],[ -73.935982114337421, 40.866846163445771],[ -74.030012249838478, 40.880202851376716]]]},
{"type": "Polygon","coordinates": [[[ -73.935982114337421, 40.866846163445771],[ -73.935982114337421, 40.787917134506841],[ -73.841906340776248, 40.774477568182071],[ -73.841906340776248, 40.853401155678846],[ -73.935982114337421, 40.866846163445771]]]}]},
"properties": {"name": "polygons"}}

The following example calculates polygon unions that represent S2 cell and its neighbors.

Run the query

let s2cell = '89c259';
print cells = array_concat(pack_array(s2cell), geo_s2cell_neighbors(s2cell))
| mv-expand cells to typeof(string)
| project polygons = geo_s2cell_to_polygon(cells)
| summarize arr = make_list(polygons)
| project polygon = geo_union_polygons_array(arr)

Output

polygon
{"type": "Polygon","coordinates": [[[-73.841906340776248,40.695446474556284],[-73.841906340776248,40.774477568182071],[-73.841906340776248,40.853401155678846],[-73.935982114337421,40.866846163445771],[-74.030012249838478,40.880202851376716],[-74.1239959854733,40.893471289549758],[-74.1239959854733,40.814531536204242],[-74.1239959854733,40.735483949993387],[-74.1239959854733,40.656328734184143],[-74.030012249838478,40.643076628676461],[-73.935982114337421,40.629736433321796],[-73.841906340776248,40.616308079144915],[-73.841906340776248,40.695446474556284]]]}

The following example returns true because of the invalid S2 Cell token input.

Run the query

print invalid = isnull(geo_s2cell_neighbors('a'))

Output

invalid
1