given a PostGIS table `lname` with `lat` and `lon` columns and primay key `gid`, make a cluster filtering by `filtercol` column with `filterval` value and excluding `excludecol` column with `excludeval` value

postgis-cluster-lat-lon-with-filters.sql

CREATE OR REPLACE FUNCTION get_domains_n(lname varchar, lat varchar, lon varchar, gid varchar, radius numeric, filtercol varchar, filterval varchar, excludecol varchar, excludeval varchar)
    RETURNS SETOF record AS
$$
DECLARE
    lid_new    integer;
    dmn_number integer := 1;
    outr       record;
    innr       record;
    r          record;
BEGIN

    DROP TABLE IF EXISTS tmp;
    EXECUTE format('CREATE TEMPORARY TABLE tmp AS SELECT %I, ST_GeometryFromText('''||Concat('POINT(''||','%I','||'' ''||','%I','||'')')||''') AS geom FROM %I WHERE %I != %L AND %I = %L ', gid, lat, lon, lname, excludecol, excludeval, filtercol, filterval);
    ALTER TABLE tmp ADD COLUMN dmn integer;
    ALTER TABLE tmp ADD COLUMN chk boolean DEFAULT FALSE;
    EXECUTE 'UPDATE tmp SET dmn = '||dmn_number||', chk = FALSE WHERE '||gid||' = (SELECT MIN('||gid||') FROM tmp)';

    LOOP
        LOOP
            FOR outr IN EXECUTE 'SELECT '||gid||' AS gid, geom FROM tmp WHERE dmn = '||dmn_number||' AND NOT chk' LOOP
                FOR innr IN EXECUTE 'SELECT '||gid||' AS gid, geom FROM tmp WHERE dmn IS NULL' LOOP
                    IF ST_DWithin(ST_Transform(ST_SetSRID(outr.geom, 4326), 3785), ST_Transform(ST_SetSRID(innr.geom, 4326), 3785), radius) THEN
                        EXECUTE 'UPDATE tmp SET dmn = '||dmn_number||', chk = FALSE WHERE '||gid||' = '||innr.gid;
                    END IF;
                END LOOP;
                EXECUTE 'UPDATE tmp SET chk = TRUE WHERE '||gid||' = '||outr.gid;
            END LOOP;
            SELECT INTO r dmn FROM tmp WHERE dmn = dmn_number AND NOT chk LIMIT 1;
            EXIT WHEN NOT FOUND;
       END LOOP;
       SELECT INTO r dmn FROM tmp WHERE dmn IS NULL LIMIT 1;
       IF FOUND THEN
           dmn_number := dmn_number + 1;
           EXECUTE 'UPDATE tmp SET dmn = '||dmn_number||', chk = FALSE WHERE '||gid||' = (SELECT MIN('||gid||') FROM tmp WHERE dmn IS NULL LIMIT 1)';
       ELSE
           EXIT;
       END IF;
    END LOOP;

    RETURN QUERY EXECUTE 'SELECT ST_ConvexHull(ST_Collect(geom)) FROM tmp GROUP by dmn';

    RETURN;
END
$$
LANGUAGE plpgsql;

updated the gist to use format in the main EXECUTE function so it is less vulnerable