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h3
CORE
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 Spatial Indexes section of this documentation.
H3_BOUNDARY(index)
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
SELECT CARTO.CARTO.H3_BOUNDARY('84390cbffffffff');
-- { "coordinates": [ [ [ -3.5769274353957314, 40.613438595935165 ], [ -3.85975632308016, 40.525472355369885 ], ...
H3_CENTER(index)
Description
Returns the center of the H3 cell as a GEOGRAPHY point. It will return
null
on error (invalid input).index
:STRING
The H3 cell index.
Return type
GEOGRAPHY
Example
SELECT CARTO.CARTO.H3_CENTER('84390cbffffffff');
-- { "coordinates": [ -3.6176032466282892, 40.37254058216577 ], "type": "Point" }
H3_COMPACT(indexArray)
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
SELECT CARTO.CARTO.H3_COMPACT(ARRAY_CONSTRUCT('85390ca3fffffff', '85390ca7fffffff', '85390cabfffffff', '85390caffffffff', '85390cb3fffffff', '85390cb7fffffff', '85390cbbfffffff'));
-- 84390cbffffffff
H3_DISTANCE(origin, destination)
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
SELECT CARTO.CARTO.H3_DISTANCE('84390c1ffffffff', '84390cbffffffff');
-- 1
tip
If you want the distance in meters use ST_DISTANCE between the cells (H3_BOUNDARY) or their centroid.
H3_FROMGEOGPOINT(point, resolution)
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.
Return type
STRING
Example
SELECT CARTO.CARTO.H3_FROMGEOGPOINT(ST_POINT(-3.7038, 40.4168), 4);
-- 84390cbffffffff
tip
H3_FROMLONGLAT(longitude, latitude, resolution)
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.
Return type
STRING
Example
SELECT CARTO.CARTO.H3_FROMLONGLAT(-3.7038, 40.4168, 4);
-- 84390cbffffffff
H3_HEXRING(origin, size)
Description
Returns all cell indexes in a hollow hexagonal ring centered at the origin in no particular order. Unlike H3_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
SELECT CARTO.CARTO.H3_HEXRING('84390cbffffffff', 1);
-- 84392b5ffffffff
-- 84390c9ffffffff
-- 84390c1ffffffff
-- 84390c3ffffffff
-- 84390ddffffffff
-- 84392b7ffffffff
H3_INT_TOSTRING(index)
Description
Converts the integer representation of the H3 index to the string representation.
index
:INT
The H3 cell index.
Return type
STRING
Example
SELECT CARTO.CARTO.H3_INT_TOSTRING(595478781590765567);
-- 84390cbffffffff
H3_ISPENTAGON(index)
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
SELECT CARTO.CARTO.H3_ISPENTAGON('84390cbffffffff');
-- false
SELECT CARTO.CARTO.H3_ISPENTAGON('8075fffffffffff');
-- true
H3_ISVALID(index)
Description
Returns
true
when the given index is valid, false
otherwise.index
:STRING
The H3 cell index as hexadecimal.
Return type
BOOLEAN
Examples
SELECT CARTO.CARTO.H3_ISVALID('84390cbffffffff');
-- true
SELECT CARTO.CARTO.H3_ISVALID('1');
-- false
H3_KRING(origin, size)
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
SELECT CARTO.CARTO.H3_KRING('84390cbffffffff', 1);
-- 84390cbffffffff
-- 84390c9ffffffff
-- 84390c1ffffffff
-- 84390c3ffffffff
-- 84390ddffffffff
-- 84392b7ffffffff
-- 84392b5ffffffff
H3_KRING_DISTANCES(origin, size)
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
SELECT CARTO.CARTO.H3_KRING_DISTANCES('84390cbffffffff', 1);
-- {"index": "84390cbffffffff", "distance": 0}
-- {"index": "84390c9ffffffff", "distance": 1}
-- {"index": "84390c1ffffffff", "distance": 1}
-- {"index": "84390c3ffffffff", "distance": 1}
-- {"index": "84390ddffffffff", "distance": 1}
-- {"index": "84392b7ffffffff", "distance": 1}
-- {"index": "84392b5ffffffff", "distance": 1}
H3_POLYFILL(geography, resolution)
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 shape to cover.
Return type
ARRAY
Example
SELECT CARTO.CARTO.H3_POLYFILL(
TO_GEOGRAPHY('POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))'), 4);
-- 842da29ffffffff
-- 843f725ffffffff
-- 843eac1ffffffff
-- 8453945ffffffff
-- ...
H3_POLYFILL_TABLE(input_query, resolution, mode, output_table)
Description
Returns a table with the H3 cell indexes contained in the given geography at a given level of detail. Containment is determined by the mode: center, intersects, contains. All the attributes except the geography will be included in the output table, clustered by the h3 column.
input_query
:STRING
input data to polyfill. It must contain a columngeom
with the shape to cover. Additionally, other columns can be included.mode
:STRING
center
returns the indexes of the H3 cells which centers intersect the input geography (polygon). The resulting H3 set does not fully cover the input geography, however, this is significantly faster that the other modes. This mode is not compatible with points or lines. Equivalent toH3_POLYFILL
.intersects
returns the indexes of the H3 cells that intersect the input geography. The resulting H3 set will completely cover the input geography (point, line, polygon).contains
returns the indexes of the H3 cells that are entirely contained inside the input geography (polygon). This mode is not compatible with points or lines.
output_table
:STRING
name of the output table to store the results of the polyfill.
Mode
center
:
Mode
intersects
:
Mode
contains
:
Output
The results are stored in the table named
<output_table>
, which contains the following columns:h3
:STRING
the geometry of the considered point.- The rest of columns included in
input_query
exceptgeom
.
Examples
CALL CARTO.CARTO.H3_POLYFILL_TABLE(
'SELECT TO_GEOGRAPHY(''POLYGON ((-3.71219873428345 40.413365349070865, -3.7144088745117 40.40965661286395, -3.70659828186035 40.409525904775634, -3.71219873428345 40.413365349070865))'') AS geom',
9, 'intersects',
'<database>.<schema>.<output_table>'
);
-- The table `<database>.<schema>.<output_table>` will be created
-- with column: h3
CALL CARTO.CARTO.H3_POLYFILL_TABLE(
'SELECT geom, name, value FROM `<database>.<schema>.<table>`',
9, 'center',
'<database>.<schema>.<output_table>'
);
-- The table `<database>.<schema>.<output_table>` will be created
-- with columns: h3, name, value
H3_RESOLUTION(index)
Description
Returns the H3 cell resolution as an integer. It will return
null
on error (invalid input).index
:STRING
The H3 cell index.
Return type
INT
Example
SELECT CARTO.CARTO.H3_RESOLUTION('84390cbffffffff');
-- 4
H3_STRING_TOINT(index)
Description
Converts the string representation of the H3 index to the integer representation.
index
:STRING
The H3 cell index.
Return type
INT
Example
SELECT CARTO.CARTO.H3_STRING_TOINT('84390cbffffffff');
-- 595478781590765567
H3_TOCHILDREN(index, resolution)
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.
Return type
ARRAY
Example
SELECT CARTO.CARTO.H3_TOCHILDREN('83390cfffffffff', 4);
-- 84390c1ffffffff
-- 84390c3ffffffff
-- 84390c5ffffffff
-- 84390c7ffffffff
-- 84390c9ffffffff
-- 84390cbffffffff
-- 84390cdffffffff
H3_TOPARENT(index, resolution)
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.
Return type
STRING
Example
SELECT CARTO.CARTO.H3_TOPARENT('84390cbffffffff', 3);
-- 83390cfffffffff
H3_UNCOMPACT(indexArray, resolution)
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.
Return type
ARRAY
Example
SELECT CARTO.CARTO.H3_UNCOMPACT(ARRAY_CONSTRUCT('84390cbffffffff'), 5);
-- 85390ca3fffffff
-- 85390ca7fffffff
-- 85390cabfffffff
-- 85390caffffffff
-- 85390cb3fffffff
-- 85390cb7fffffff
-- 85390cbbfffffff
Last modified 1mo ago