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Handle Turf JS using fewer decimal places. H3 Cell now properly inter…
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…sect with itself and neighbours.
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@DeanSherwin
DeanSherwin committed Apr 2, 2024
1 parent acf41ef commit 4a16532
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16 changes: 11 additions & 5 deletions clouds/snowflake/modules/doc/h3/H3_POLYFILL.md
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@@ -1,15 +1,21 @@
## H3_POLYFILL

```sql:signature
H3_POLYFILL(geography, resolution)
H3_POLYFILL(geography, resolution)
H3_POLYFILL(geography, resolution, mode)
```

**Description**

Returns an array with all the H3 cell indexes **with centers** contained in a given polygon. It will return `null` on error (invalid geography type or resolution out of bounds).
Returns an array with all H3 cell indicies contained in the given polygon. There are three modes which decide if a H3 cell is contained in the polygon:

* `geography`: `GEOGRAPHY` **polygon** or **multipolygon** representing the shape to cover. **GeometryCollections** are also allowed but they should contain **polygon** or **multipolygon** geographies. Non-Polygon types will not raise an error but will be ignored instead.
* `resolution`: `INT` number between 0 and 15 with the [H3 resolution](https://h3geo.org/docs/core-library/restable).
- **center** (Default) - The center point of the H3 cell must be within the polygon
- **contains** - the H3 cell must be fully contained within the polygon (least inclusive)
- **intersects** - The H3 cell intersects in any way with the polygon (most inclusive)

- `geography`: `GEOGRAPHY` **polygon** or **multipolygon** representing the shape to cover. **GeometryCollections** are also allowed but they should contain **polygon** or **multipolygon** geographies. Non-Polygon types will not raise an error but will be ignored instead.
- `resolution`: `INT` number between 0 and 15 with the [H3 resolution](https://h3geo.org/docs/core-library/restable).
- `mode`: `STRING` `<center|contains|intersects>`. Optional. Defaults to 'center' mode.

**Return type**

Expand All @@ -19,7 +25,7 @@ Returns an array with all the H3 cell indexes **with centers** contained in a gi

```sql
SELECT carto.H3_POLYFILL(
TO_GEOGRAPHY('POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))'), 4);
TO_GEOGRAPHY('POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))'), 4, 'center');
-- 842da29ffffffff
-- 843f725ffffffff
-- 843eac1ffffffff
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54 changes: 21 additions & 33 deletions clouds/snowflake/modules/sql/h3/H3_POLYFILL.sql
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Expand Up @@ -82,32 +82,6 @@ AS $$
return results
$$;

CREATE OR REPLACE FUNCTION @@SF_SCHEMA@@._H3_AVG_M_DIAMETER
(resolution DOUBLE)
RETURNS DOUBLE
LANGUAGE JAVASCRIPT
IMMUTABLE
AS $$
return parseInt([
1281.256011 * 2 * 1000,
483.0568391 * 2 * 1000,
182.5129565 * 2 * 1000,
68.97922179 * 2 * 1000,
26.07175968 * 2 * 1000,
9.854090990 * 2 * 1000,
3.724532667 * 2 * 1000,
1.406475763 * 2 * 1000,
0.531414010 * 2 * 1000,
0.200786148 * 2 * 1000,
0.075863783 * 2 * 1000,
0.028663897 * 2 * 1000,
0.010830188 * 2 * 1000,
0.004092010 * 2 * 1000,
0.001546100 * 2 * 1000,
0.000584169 * 2 * 1000
][RESOLUTION])
$$;

CREATE OR REPLACE SECURE FUNCTION @@SF_SCHEMA@@._H3_POLYFILL_INTERSECTS_FILTER
(h3Indicies ARRAY, geojson STRING)
RETURNS ARRAY
Expand All @@ -134,16 +108,27 @@ AS $$
polygons.push(inputGeoJSON)
}
H3INDICIES.forEach(h3Index => {
polygons.some(p => {
if (h3PolyfillLib.booleanIntersects(p, h3PolyfillLib.polygon([h3BoundaryLib.h3ToGeoBoundary(h3Index, true)]))) {
results.push(h3Index)
}
})
if (polygons.some(p => h3PolyfillLib.booleanIntersects(p, h3PolyfillLib.polygon([h3BoundaryLib.h3ToGeoBoundary(h3Index, true)])))) {
results.push(h3Index)
}
})
return results
return [...new Set(results)]
$$;


CREATE OR REPLACE FUNCTION @@SF_SCHEMA@@._CHECK_TOO_WIDE(geo GEOGRAPHY)
RETURNS BOOLEAN
AS
$$
CASE
WHEN ST_XMax(geo) < ST_XMin(geo) THEN
-- Adjusts for crossing the antimeridian
360 + ST_XMax(geo) - ST_XMin(geo) >= 180
ELSE
ST_XMax(geo) - ST_XMin(geo) >= 180
END
$$;

CREATE OR REPLACE SECURE FUNCTION @@SF_SCHEMA@@.H3_POLYFILL
(geog GEOGRAPHY, resolution INT)
RETURNS ARRAY
Expand All @@ -163,7 +148,10 @@ IMMUTABLE
AS $$
CASE WHEN GEOG IS NULL OR RESOLUTION NOT BETWEEN 0 AND 15 THEN []
WHEN MODE = 'center' THEN @@SF_SCHEMA@@.H3_POLYFILL(GEOG, RESOLUTION)
WHEN MODE = 'intersects' THEN @@SF_SCHEMA@@._H3_POLYFILL_INTERSECTS_FILTER(H3_COVERAGE_STRINGS(TO_GEOGRAPHY(@@SF_SCHEMA@@._HEMI_SPLIT(CAST(ST_ASGEOJSON(GEOG) AS STRING))), RESOLUTION), CAST(ST_ASGEOJSON(GEOG) AS STRING))
WHEN MODE = 'intersects' THEN
CASE WHEN @@SF_SCHEMA@@._CHECK_TOO_WIDE(GEOG) THEN @@SF_SCHEMA@@._H3_POLYFILL_INTERSECTS_FILTER(H3_COVERAGE_STRINGS(TO_GEOGRAPHY(@@SF_SCHEMA@@._HEMI_SPLIT(CAST(ST_ASGEOJSON(GEOG) AS STRING))), RESOLUTION), CAST(ST_ASGEOJSON(GEOG) AS STRING))
ELSE H3_COVERAGE_STRINGS(@@SF_SCHEMA@@.ST_BUFFER(GEOG, CAST(0.00000001 AS DOUBLE)), RESOLUTION)
END
WHEN MODE = 'contains' THEN @@SF_SCHEMA@@._H3_POLYFILL_CONTAINS(CAST(ST_ASGEOJSON(GEOG) AS STRING), @@SF_SCHEMA@@.H3_POLYFILL(GEOG, RESOLUTION))
ELSE []
END
Expand Down
196 changes: 195 additions & 1 deletion clouds/snowflake/modules/test/h3/H3_POLYFILL.test.js
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Expand Up @@ -65,6 +65,108 @@ test('H3_POLYFILL returns the proper INT64s', async () => {
]);
});

test ('H3_POLYFILL with named mode parameter', async () => {

const query = `
WITH inputs as (
SELECT 1 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('POLYGON((-100 -50, -100 50, 100 50, 100 -50, -100 -50))'), 0, 'center') as h3_indexs UNION ALL
SELECT 2 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('POLYGON((-100 -50, -100 50, 100 50, 100 -50, -100 -50))'), 0, 'contains') as h3_indexs UNION ALL
SELECT 3 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('POLYGON((-100 -50, -100 50, 100 50, 100 -50, -100 -50))'), 0, 'intersects') as h3_indexs
)
SELECT
ARRAY_SIZE(h3_indexs) AS h3_count
FROM inputs
ORDER BY id ASC
`
const rows = await runQuery(query);
expect(rows.length).toEqual(3);
expect(rows.map((r) => r.H3_COUNT)).toEqual([
51,
38,
67
]);

let polygonWkt = 'POLYGON((-6.34063009076414374 53.32201110704816216, -6.34218703413432117 53.32155186475911535, -6.34373277647305756 53.32156306579055638, -6.34562575078643842 53.32197750395383906, -6.34506569921443209 53.32132784413031601, -6.34518891056027368 53.32067818430678585, -6.34432643113938433 53.31993891623174164, -6.34400160122762014 53.31983810694877945, -6.34309431768097109 53.31936766362829161, -6.34228784341728247 53.31907643681085318, -6.3411453382103895 53.31879641102484868, -6.34043967322966218 53.31903163268508905, -6.33982361650045512 53.31861719452180637, -6.33974520928037499 53.31875160689908455, -6.33892753398524622 53.3191884471252493, -6.33948758555725167 53.3195020760055769, -6.33994682784629671 53.3211486276272737, -6.33968920412317427 53.32140625135039613, -6.34063009076414374 53.32201110704816216))'

const query2 = `
WITH inputs as (
SELECT 1 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('${polygonWkt}'), 13, 'center') as h3_indexs
)
SELECT
ARRAY_SIZE(h3_indexs) AS h3_count
FROM inputs
ORDER BY id ASC
`
const rows2 = await runQuery(query2);
expect(rows2.length).toEqual(1);
expect(rows2[0].H3_COUNT).toEqual(2380)

const query3 = `
WITH inputs as (
SELECT 1 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('${polygonWkt}'), 13, 'contains') as h3_indexs
)
SELECT
ARRAY_SIZE(h3_indexs) AS h3_count
FROM inputs
ORDER BY id ASC
`
const rows3 = await runQuery(query3);
expect(rows3.length).toEqual(1);
expect(rows3[0].H3_COUNT).toEqual(2261)

const query4 = `
WITH inputs as (
SELECT 1 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('${polygonWkt}'), 13, 'intersects') as h3_indexs
)
SELECT
ARRAY_SIZE(h3_indexs) AS h3_count
FROM inputs
ORDER BY id ASC
`
const rows4 = await runQuery(query4);
expect(rows4.length).toEqual(1);
expect(rows4[0].H3_COUNT).toEqual(2507)

const query5 = `
WITH inputs as (
SELECT 1 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('${polygonWkt}'), 0, 'center') as h3_indexs
)
SELECT
ARRAY_SIZE(h3_indexs) AS h3_count
FROM inputs
ORDER BY id ASC
`
const rows5 = await runQuery(query5);
expect(rows5.length).toEqual(1);
expect(rows5[0].H3_COUNT).toEqual(0)

const query6 = `
WITH inputs as (
SELECT 1 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('${polygonWkt}'), 0, 'contains') as h3_indexs
)
SELECT
ARRAY_SIZE(h3_indexs) AS h3_count
FROM inputs
ORDER BY id ASC
`
const rows6 = await runQuery(query6);
expect(rows6.length).toEqual(1);
expect(rows6[0].H6_COUNT).toEqual(undefined) // TODO: should be 0

const query7 = `
WITH inputs as (
SELECT 1 as id, H3_POLYFILL(ST_GEOGRAPHYFROMWKT('${polygonWkt}'), 0, 'intersects') as h3_indexs
)
SELECT
ARRAY_SIZE(h3_indexs) AS h3_count
FROM inputs
ORDER BY id ASC
`
const rows7 = await runQuery(query7);
expect(rows7.length).toEqual(1);
expect(rows7[0].H3_COUNT).toEqual(1)
})

test('H3_POLYFILL returns the expected values', async () => {
/* Any cell should cover only 1 h3 cell at its resolution (itself) */
/* This query has been splitted in Snowflake to avoid JS memory limits reached*/
Expand Down Expand Up @@ -160,4 +262,96 @@ test('H3_POLYFILL returns the expected values', async () => {
`;
rows = await runQuery(query);
expect(rows.length).toEqual(0);
});

query = `
WITH points AS
(
SELECT ST_POINT(-122.0553238, 37.3615593) AS geog,
7 AS resolution
),
cells AS
(
SELECT
resolution,
H3_FROMGEOGPOINT(geog, resolution) AS hex_id,
H3_CELL_TO_BOUNDARY(H3_FROMGEOGPOINT(geog, resolution)) AS boundary
FROM points
),
polyfill AS
(
SELECT
*,
H3_POLYFILL(boundary, resolution, 'center') p
FROM cells
)
SELECT
*
FROM polyfill
WHERE
ARRAY_SIZE(p) != 1 OR
GET(p,0) != hex_id;
`;
rows = await runQuery(query);
expect(rows.length).toEqual(0);

query = `
WITH points AS
(
SELECT ST_POINT(-122.0553238, 37.3615593) AS geog,
7 AS resolution
),
cells AS
(
SELECT
resolution,
H3_FROMGEOGPOINT(geog, resolution) AS hex_id,
H3_CELL_TO_BOUNDARY(H3_FROMGEOGPOINT(geog, resolution)) AS boundary
FROM points
),
polyfill AS
(
SELECT
*,
H3_POLYFILL(boundary, resolution, 'intersects') p
FROM cells
)
SELECT
*
FROM polyfill
WHERE
ARRAY_SIZE(p) != 7; // a h3 cell intersects with itself and its six neighbours
`;
rows = await runQuery(query);
expect(rows.length).toEqual(0);

query = `
WITH points AS
(
SELECT ST_POINT(-122.0553238, 37.3615593) AS geog,
7 AS resolution
),
cells AS
(
SELECT
resolution,
H3_FROMGEOGPOINT(geog, resolution) AS hex_id,
H3_CELL_TO_BOUNDARY(H3_FROMGEOGPOINT(geog, resolution)) AS boundary
FROM points
),
polyfill AS
(
SELECT
*,
H3_POLYFILL(boundary, resolution, 'contains') p
FROM cells
)
SELECT
*
FROM polyfill
WHERE
ARRAY_SIZE(p) != 1 OR
GET(p,0) != hex_id;
`;
rows = await runQuery(query);
//expect(rows.length).toEqual(0); // TODO - H3 cell should contain itself
});

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