1
vote
0answers
53 views

How to count the number of coordinates within x meters grouping by distinct ids?

I have a table "items" of about 1 million rows and 40.000 distinct ids like the following: idx | id | point | lat | lon | the_geom 1 | 1 | 76 | 51.463388 | -0.16869856 | 0101000020E... 2 | 1 | 53 | ...
0
votes
0answers
47 views

pgrouting pgr_drivingdistance() query gives inconsistent results

So I have been working on a query(with the help of other stackexchangers :)) to get the edges in an isochrone from a particular point and then update the count_events field of those edges by some ...
1
vote
1answer
67 views

Problem with runing a loop in a query in PostGIS

I am new to PostGIS and I have a question which can't solve. I have a table of buildings each having a value for number of people living in it. I would like to calculate the total value (sum of number ...
0
votes
2answers
60 views

Select area which is at least x meters away from other geometries

In my table I have the build-up area from a region as a big number of polygons. urban_area: id | name | geometry(polygon) I was wondering if and how I would be able to find the area within a ...
8
votes
1answer
284 views

What is the precision of SELECT DISTINCT on PostGIS geometry column?

I wonder what the precision of the SELECT DISTINCT operator is on a PostGIS geometry. On my system, the following query gives me a count of 5, which means that the inserted points are considered equal ...
0
votes
2answers
206 views

PostGIS, distance between two users

I have a simple table (location_test) with three column (name, geom , jid). geom is a geometry column with SRID 27700. I set the user's geometry position with: UPDATE location_test SET geom = ...
2
votes
1answer
223 views

How to filter or query data in GRASS?

I have a PostGIS dataset with just over 2 million rows. Each row has a PostGIS geometry point value and several attributes. I'd like to do some analysis on certain subsets of the data, but I can't ...
4
votes
1answer
1k views

How to find the nearest point by using PostGIS function?

table A: lat | long | the_geom | code | sign 13.8433095 | 100.6360357 | 0101000020E61.... | ABC | start_point 13.7544738 | 100.5459646 | 0101000020E6..... | ABC | end_point 13.4124215 | 100.6232332 ...