clustering

This module contains functions that perform clustering on geographies.

ST_CLUSTERKMEANS

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: ARRAY points to be clustered.

• numberOfClusters (optional): INT numberOfClusters that will be generated. By default numberOfClusters is Math.sqrt(<NUMBER OF POINTS>/2). The output number of cluster cannot be greater to the number of distinct points of the geojsons.

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

• New supplier offices based on store locations clusters