如何通过两列聚合多个点并从中创建一个LineString / MultiLineString

问题描述 投票:1回答:1

我有一个名为包含这些行的位置的表:

id uuid NOT NULL,
"deviceId" text COLLATE pg_catalog."default",
"userId" uuid,
"userName" text COLLATE pg_catalog."default",
"creationDateTime" timestamp with time zone,
shape geometry,
CONSTRAINT id PRIMARY KEY (id)

想象一下,我的用户在shape列中将每小时的点数记录到此表中。当注册登记到表中的那个点的时间时,保存到像creationDateTime这样的2018-08-22 00:03:41.649+04:30列中。

我如何提取此信息:

each User ---- each day ---- list of geometry(shape column)在例子中:

第一天的User1具有几何点列表。第二天的User1有几何点列表,依此类推......

我通过mongo为同一个项目做了这个查询:

{$project: {
    _id: 0,
    uId : "$UserId",
    dId : "$DeviceId",
    ts :"$CreationDateTime",
    point : "$Point"
    }
 }, 
{$group: {
    _id :{
        did: "$dId",
        day: { $dayOfMonth: "$ts" }
    },
    docs: { $push: "$$ROOT" }
     }
 },

 {
    $sort:{"_id.day": -1}
 }

但是我怎么能用postgresql做到这一点? postgre上没有这种聚合,我在postgresql上是新的。这是我的查询:

(Select test1."deviceId",test1."shape", test1."creationDateTime" From   
    (Select * from locations) as test1 Group By test1."deviceId",test1."shape",test1."creationDateTime"
ORDER BY  test1."creationDateTime")

此查询没有合适的结果,我知道此查询有问题。用户的deviceId经常与其他行重复。我如何处理它?

最后,我想创建多折线per user - per day - multi poly line

sql postgresql postgis
1个回答
2
投票

可能有一百万种方法可以回答这个问题。这是其中之一:

考虑你的桌面结构..

CREATE TEMPORARY TABLE locations
(id uuid,
deviceId text COLLATE pg_catalog."default",
userId uuid,
userName text COLLATE pg_catalog."default",
creationDateTime timestamp with time zone,
shape geometry);

..以及这些样本数据..

INSERT INTO locations (userId, creationDateTime, shape) 
VALUES ('d1166a84-ab66-11e8-98d0-529269fb1459',CURRENT_DATE,'POINT(-1.25 51.75)'),
       ('d1166a84-ab66-11e8-98d0-529269fb1459',CURRENT_DATE,'POINT(-1.15 52.96)'),
       ('d1166a84-ab66-11e8-98d0-529269fb1459',CURRENT_DATE,'POINT(-0.13 50.82)'),
       ('d1166a84-ab66-11e8-98d0-529269fb1459',CURRENT_DATE-1,'POINT(-2.22 53.48)'),
       ('d1166a84-ab66-11e8-98d0-529269fb1459',CURRENT_DATE-1,'POINT(-0.11 51.51)');

..你可以聚合每个用户的点数+日期,并使用LINESTRINGST_MakeLine创建一个GROUP BY

SELECT userId, creationDateTime, ST_AsText(ST_MakeLine(shape))
FROM locations
GROUP BY userId, creationDateTime
ORDER BY  creationDateTime;

                userid                |    creationdatetime    |                    st_astext                    
--------------------------------------+------------------------+-------------------------------------------------
 d1166a84-ab66-11e8-98d0-529269fb1459 | 2018-08-28 00:00:00+02 | LINESTRING(-2.22 53.48,-0.11 51.51)
 d1166a84-ab66-11e8-98d0-529269fb1459 | 2018-08-29 00:00:00+02 | LINESTRING(-1.25 51.75,-1.15 52.96,-0.13 50.82)
(2 Zeilen)

用户d1166a84-ab66-11e8-98d0-529269fb14592018-08-28 00:00:00+02 enter image description here的图形描述

以同样的方式,你可以使用MULTIPOINT创建一个ST_Collect

SELECT userId, creationDateTime, ST_AsText(ST_Collect(shape))
FROM locations
GROUP BY userId, creationDateTime
ORDER BY  creationDateTime;

                userid                |    creationdatetime    |                    st_astext                    
--------------------------------------+------------------------+-------------------------------------------------
 d1166a84-ab66-11e8-98d0-529269fb1459 | 2018-08-28 00:00:00+02 | MULTIPOINT(-2.22 53.48,-0.11 51.51)
 d1166a84-ab66-11e8-98d0-529269fb1459 | 2018-08-29 00:00:00+02 | MULTIPOINT(-1.25 51.75,-1.15 52.96,-0.13 50.82)
(2 Zeilen)

enter image description here

编辑 - 使用LINESTRINGS(aka WITH Clause)为每个用户(MULTILINESTRING)每天创建一组CTE

WITH j AS (
  SELECT userId, creationDateTime, ST_MakeLine(shape) AS shape
  FROM locations
  GROUP BY userId, creationDateTime)
SELECT userId, ST_AsText(ST_Collect(shape))
FROM j
GROUP BY userId

                userid                |                                    st_astext                                     
--------------------------------------+----------------------------------------------------------------------------------
 d1166a84-ab66-11e8-98d0-529269fb1459 | MULTILINESTRING((-2.22 53.48,-0.11 51.51),(-1.25 51.75,-1.15 52.96,-0.13 50.82))
(1 

enter image description here

基本上你要做的就是对你需要的记录进行分组(在这种情况下是用户和日期)并使用你选择的聚合函数,例如: ST_MergeLineST_CollectST_UnionST_Multi等。

© www.soinside.com 2019 - 2024. All rights reserved.