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clustering
CORE
This module contains functions that perform clustering on geographies.
ST_CLUSTERKMEANS(geog [, numberOfClusters])
Description
Takes a set of points as input and partitions them into clusters using the k-means algorithm. Returns an array of tuples with the cluster index for each of the input features and the input geometry.
geojsons:ARRAYpoints to be clustered.numberOfClusters(optional):INTnumberOfClusters that will be generated. By defaultnumberOfClustersisMath.sqrt(<NUMBER OF POINTS>/2).
Return type
ARRAY: containing objects with cluster, as the cluster id, and geom, as the geometry geojson.Examples
SELECT CARTO.CARTO.ST_CLUSTERKMEANS(ARRAY_CONSTRUCT(ST_ASGEOJSON(ST_POINT(0, 0))::STRING, ST_ASGEOJSON(ST_POINT(0, 1))::STRING, ST_ASGEOJSON(ST_POINT(5, 0))::STRING, ST_ASGEOJSON(ST_POINT(1, 0))::STRING));
-- {"cluster": 0, "geom": "{\"coordinates\":[0,0],\"type\":\"Point\"}"}
-- {"cluster": 0, "geom": "{\"coordinates\":[0,1],\"type\":\"Point\"}"}
-- {"cluster": 0, "geom": "{\"coordinates\":[5,0],\"type\":\"Point\"}"}
-- {"cluster": 0, "geom": "{\"coordinates\":[1,0],\"type\":\"Point\"}"}
SELECT CARTO.CARTO.ST_CLUSTERKMEANS(ARRAY_CONSTRUCT(ST_ASGEOJSON(ST_POINT(0, 0))::STRING, ST_ASGEOJSON(ST_POINT(0, 1))::STRING, ST_ASGEOJSON(ST_POINT(5, 0))::STRING, ST_ASGEOJSON(ST_POINT(1, 0))::STRING), 2);
-- {"cluster": 1, "geom": "{\"coordinates\":[0,0],\"type\":\"Point\"}"}
-- {"cluster": 1, "geom": "{\"coordinates\":[0,1],\"type\":\"Point\"}"}
-- {"cluster": 0, "geom": "{\"coordinates\":[5,0],\"type\":\"Point\"}"}
-- {"cluster": 1, "geom": "{\"coordinates\":[1,0],\"type\":\"Point\"}"}
Additional examples
Last modified 8mo ago