I am trying to cluster latitudes and longitudes from a dataset containing locations in Germany (n=52612, about 9000 without duplicates). I am running the DBSCAN algorithm, but for none of the parameter values I have tried, I am getting any clusters- the cluster ID is 0 for all rows (I have also tried all coordinates vs. only unique ones). I did a similar exercise with Python's DBSCAN in sklearn and got some clusters there for a broad range of parameter values. What is wrong here?
eps = 20000 corresponds to 20km, is that correct? Anyway, I don't get any results irrespective of the eps-value
--add geometry ALTER TABLE table ADD COLUMN geom GEOMETRY; UPDATE table SET geom = (ST_SetSRID(ST_MakePoint(lng,lat),4326)) ; CREATE INDEX gix ON table USING GIST (geom); --cluster SELECT *, ST_ClusterDBSCAN(geom::geometry, eps := 20000, minpoints := 100) over () AS cluster_id FROM table WHERE year = 2010 and country = 'Germany'