在PostgreSQL/PostGIS中生成餅狀楔（幾何圖形）的ID

Question

我有一個查詢，在點圖層周圍50米的圓（緩衝區）中生成12個部分（餅狀楔）。

With buffer as(
SELECT gid as pt_id, (ST_DumpPoints(ST_Buffer(geom,50,3))).geom as geom 
FROM my_point_table group by gid, geom 
UNION ALL 
SELECT gid as pt_id, geom FROM my_point_table 
) 
SELECT gid, (ST_Dump(ST_DelaunayTriangles(ST_Collect(geom),0, 0))).geom geom 
FROM buffer 
GROUP BY pt_id 

我想ID指派給這些部分是這樣的：如何做到這將高度讚賞

建議。

Answer 1

你可以嘗試這樣的事情

With my_point_table as (
    select 1 as gid, 'POINT(0 0)'::geometry as geom 
    union 
    select 2 as gid, 'POINT(1 1)'::geometry as geom 
), buffer as(
    SELECT gid as pt_id, (ST_DumpPoints(ST_Buffer(geom,50,3))).geom as geom 
    FROM my_point_table group by gid, geom 
    UNION ALL 
    SELECT gid as pt_id, geom FROM my_point_table 
) , tr as (
    SELECT pt_id, (ST_Dump(ST_DelaunayTriangles(ST_Collect(geom),0, 0))).geom geom 
    FROM buffer 
    GROUP BY pt_id 
) 
select row_number() OVER (partition by pt_id), pt_id, geom from tr 

第一部分是嘲笑你的「my_point_table」表。

row_number（）OVER（由pt_id分區） 是爲每個要素生成一個序列號。