找到离其余物体最远的物体

Question

岛上各处都有点，但很明显有一个点就是我要找的点

我运行在处理空间日期时遇到了 Postgres 中的问题。我有一个 table 列：对象 ID、纬度、经度和几何。我需要找到离其余最远的对象（点）。我该怎么做？

数据

CREATE TABLE cultural_sites
(
    cult_site_id text COLLATE pg_catalog."default" NOT NULL,
    name text COLLATE pg_catalog."default",
    type_id integer,
    found_year integer,
    prot_cat_id integer,
    closest_house_id integer,
    lat double precision,
    "long" double precision,
    geom geometry(Point,4326),
    CONSTRAINT cult_site_id PRIMARY KEY (cult_site_id)
);

INSERT INTO cultural_sites(cult_site_id, lat, long)
VALUES (923048800130006, 46.152222, 33.7015), (911711012380005, 44.43722, 34.104166), (911711012630005, 44.42833, 34.1225), (911710892610005, 44.95, 34.097222), (911710892840005, 44.958084, 34.106479), (911710988820005, 44.947788, 34.099440), (911710988990005, 44.952224, 34.095908), (911710989390005, 44.9449409, 34.097), (911710989490005, 44.955555, 34.093888), (911710989510005, 44.946944, 34.1019444);

ALTER TABLE cultural_sites
ALTER COLUMN geom
type geometry(Point,4326) using st_point(long,lat);

Answer 1

做一个自连接来计算参考点到 table 中最远点的距离，在外部查询中用 ORDER BY 和 [=12= 再次过滤它] 求最长距离：

SELECT t1.geom,t1.geom <-> j.geom AS distance
FROM cultural_sites t1
CROSS JOIN LATERAL (
  SELECT geom FROM cultural_sites t2    
  WHERE NOT t1.geom = t2.geom
  ORDER BY t1.geom <-> t2.geom
  LIMIT 1) j 
ORDER BY 2 DESC
LIMIT 1;

                        geom                        |      distance      
----------------------------------------------------+--------------------
 0101000020E61000006F1283C0CAD94040A9DDAF027C134740 | 1.2593570786051942

演示：db<>fiddle

找到离其余物体最远的物体

Find the object that is farthest from the rest

sql

postgresql

postgis

spatial