Analytics Toolbox for Snowflake

Analytics Toolbox for Snowflake

h3

H3 is Uber’s Hexagonal Hierarchical Spatial Index. Full documentation of the project can be found at h3geo. You can also learn more about H3 in the Overview section of this documentation.

COMPACT

Description

Returns an array with the indexes of a set of hexagons across multiple resolutions that represent the same area as the input set of hexagons.

  • indexArray: ARRAY of H3 cell indices of the same resolution as hexadecimal.

Return type

ARRAY

Example

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SELECT sfcarto.h3.COMPACT(ARRAY_CONSTRUCT('857b59c3fffffff', '857b59c7fffffff', '857b59cbfffffff','857b59cffffffff', '857b59d3fffffff', '857b59d7fffffff', '857b59dbfffffff'));
-- 847b59dffffffff

DISTANCE

Description

Returns the grid distance between two hexagon indexes. This function may fail to find the distance between two indexes if they are very far apart or on opposite sides of a pentagon. Returns null on failure or invalid input.

  • origin: STRING The H3 cell index as hexadecimal.
  • destination: STRING The H3 cell index as hexadecimal.

Return type

BIGINT

Example

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SELECT sfcarto.h3.DISTANCE('847b591ffffffff', '847b59bffffffff');
-- 1

HEXRING

Description

Returns all cell indexes in a hollow hexagonal ring centered at the origin in no particular order. Unlike KRING, this function will throw an exception if there is a pentagon anywhere in the ring.

  • origin: STRING H3 cell index of the origin.
  • size: INT size of the ring (distance from the origin).

Return type

ARRAY

Example

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SELECT sfcarto.h3.HEXRING('837b59fffffffff', 1);
-- 837b5dfffffffff
-- 837b58fffffffff
-- 837b5bfffffffff
-- 837a66fffffffff
-- 837a64fffffffff
-- 837b4afffffffff

ISPENTAGON

Description

Returns true if given H3 index is a pentagon. Returns false otherwise, even on invalid input.

  • index: STRING The H3 cell index as hexadecimal.

Return type

BOOLEAN

Example

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SELECT sfcarto.h3.ISPENTAGON('837b59fffffffff');
-- false
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SELECT sfcarto.h3.ISPENTAGON('8075fffffffffff');
-- true

ISVALID

Description

Returns true when the given index is valid, false otherwise.

  • index: STRING The H3 cell index as hexadecimal.

Return type

BOOLEAN

Examples

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SELECT sfcarto.h3.ISVALID('847b59dffffffff');
-- true
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SELECT sfcarto.h3.ISVALID('1');
-- false

KRING

Description

Returns all cell indexes in a filled hexagonal k-ring centered at the origin in no particular order.

  • origin: STRING H3 cell index of the origin.
  • size: INT size of the ring (distance from the origin).

Return type

ARRAY

Example

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SELECT sfcarto.h3.KRING('837b59fffffffff', 1);
-- 837b59fffffffff
-- 837b58fffffffff
-- 837b5bfffffffff
-- 837a66fffffffff
-- 837a64fffffffff
-- 837b4afffffffff
-- 837b5dfffffffff

KRING_DISTANCES

Description

Returns all cell indexes and their distances in a filled hexagonal k-ring centered at the origin in no particular order.

  • origin: STRING H3 cell index of the origin.
  • size: INT size of the ring (distance from the origin).

Return type

ARRAY

Example

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SELECT sfcarto.h3.KRING_DISTANCES('837b59fffffffff', 1);
-- {"index": "837b59fffffffff", "distance": 0}
-- {"index": "837b5dfffffffff", "distance": 1}
-- {"index": "837b58fffffffff", "distance": 1}
-- {"index": "837b5bfffffffff", "distance": 1}
-- {"index": "837a66fffffffff", "distance": 1}
-- {"index": "837a64fffffffff", "distance": 1}
-- {"index": "837b4afffffffff", "distance": 1}

LONGLAT_ASH3

Description

Returns the H3 cell index that the point belongs to in the required resolution. It will return null on error (resolution out of bounds).

  • longitude: DOUBLE horizontal coordinate of the map.
  • latitude: DOUBLE vertical coordinate of the map.
  • resolution: INT number between 0 and 15 with the H3 resolution.

Return type

STRING

Example

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SELECT sfcarto.h3.LONGLAT_ASH3(40.4168, -3.7038, 4);
-- 847b59dffffffff

ST_ASH3

Description

Returns the H3 cell index that the point belongs to in the required resolution. It will return null on error (invalid geography type or resolution out of bounds).

  • point: GEOGRAPHY point to get the H3 cell from.
  • resolution: INT number between 0 and 15 with the H3 resolution.

Return type

STRING

Example

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SELECT sfcarto.h3.ST_ASH3(ST_POINT(40.4168, -3.7038), 4);
-- 847b59dffffffff

ST_ASH3_POLYFILL

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).

  • geography: GEOGRAPHY polygon or multipolygon representing the area to cover.
  • resolution: INT number between 0 and 15 with the H3 resolution.

Return type

ARRAY

Example

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SELECT sfcarto.h3.ST_ASH3_POLYFILL(
    TO_GEOGRAPHY('POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))'), 4);
-- 842da29ffffffff
-- 843f725ffffffff
-- 843eac1ffffffff
-- 8453945ffffffff
-- ...

ST_BOUNDARY

Description

Returns a geography representing the H3 cell. It will return null on error (invalid input).

  • index: STRING The H3 cell index as hexadecimal.

Return type

GEOGRAPHY

Example

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SELECT sfcarto.h3.ST_BOUNDARY('847b59dffffffff');
-- { "coordinates": [ [ [ 40.46506362234518, -3.9352772457964957 ], [ 40.546540602670504, -3.706115055436962 ], ...

TOCHILDREN

Description

Returns an array with the indexes of the children/descendents of the given hexagon at the given resolution.

  • index: STRING The H3 cell index as hexadecimal.
  • resolution: INT number between 0 and 15 with the H3 resolution.

Return type

ARRAY

Example

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SELECT sfcarto.h3.TOCHILDREN('837b59fffffffff', 4);
-- 847b591ffffffff
-- 847b593ffffffff
-- 847b595ffffffff
-- 847b597ffffffff
-- 847b599ffffffff
-- 847b59bffffffff
-- 847b59dffffffff

TOPARENT

Description

Returns the H3 cell index of the parent of the given hexagon at the given resolution.

  • index: STRING The H3 cell index as hexadecimal.
  • resolution: INT number between 0 and 15 with the H3 resolution.

Return type

STRING

Example

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SELECT sfcarto.h3.TOPARENT('847b59dffffffff', 3);
-- 837b59fffffffff

UNCOMPACT

Description

Returns an array with the indexes of a set of hexagons of the same resolution that represent the same area as the compacted input hexagons.

  • indexArray: ARRAY of H3 cell indices as hexadecimal.
  • resolution: INT number between 0 and 15 with the H3 resolution.

Return type

ARRAY

Example

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SELECT sfcarto.h3.UNCOMPACT(ARRAY_CONSTRUCT('847b59dffffffff'), 5);
-- 857b59c3fffffff
-- 857b59c7fffffff
-- 857b59cbfffffff
-- 857b59cffffffff
-- 857b59d3fffffff
-- 857b59d7fffffff
-- 857b59dbfffffff

VERSION

Description

Returns the current version of the H3 module.

Return type

STRING

Example

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SELECT sfcarto.h3.VERSION();
-- 1.0.3