[pgrouting-users] best/fastest way to calculate thousands of trsp routes

McDonaldR McDonaldR at angus.gov.uk
Wed Apr 26 01:14:36 PDT 2017


Hi Vicky, Steve

Yes it’s Ordnance Survey Highways data with Road Routing Information (RRI).  You can get a small sample area at the bottom of this page - https://www.ordnancesurvey.co.uk/business-and-government/products/os-mastermap-highways-network.html

We also use the Integrated Transport Network (https://www.ordnancesurvey.co.uk/business-and-government/products/itn-layer.html) which also has turn restrictions.  Again, you can get a small sample of the data in GML format from the link at the bottom of the page.

Ordnance Survey also release an Urban Paths layer which can be integrated into the road layer for a more complete network.  Their open data road networks also work well for routing albeit without the turn restriction information.

Cheers

Ross

From: Pgrouting-users [mailto:pgrouting-users-bounces at lists.osgeo.org] On Behalf Of Vicky Vergara
Sent: 25 April 2017 20:06
To: pgRouting users mailing list
Subject: Re: [pgrouting-users] best/fastest way to calculate thousands of trsp routes

He is using ordinace surveay, he said so in this twit

On Tue, Apr 25, 2017 at 12:36 PM, Stephen Woodbridge <woodbri at swoodbridge.com<mailto:woodbri at swoodbridge.com>> wrote:
Hi Ross,

Out of curiosity, what data are you using? Ordinance Survey? or OSM or something else.

We hope to have a GSoC student do some work on the TRSP code. Ideally, we would like to migrate that code to use boost graph and to bring it in alignment with the other Dijkstra functions.

Most real world routing application need support for turn restriction, OSM has been adding them but it will be a while before they are well represented in most areas and that leaves data commercial data sets as the only source for routable data that contains turn restrictions. I pretty sure that Ordinance Survey has them as does Nokia HERE.

Thanks for sharing you stored procedure, I'm sure others can learn a lot from it.

Best regards,
  -Steve


On 4/25/2017 12:15 PM, McDonaldR wrote:
Hi Steve

Thanks for the pointers - I've got it working now.  It's much slower than node to node (about 0.8s per route compared to about 0.3s per route) but a more accurate result.

The function FWIW:

CREATE OR REPLACE FUNCTION corporate.pupil_journeys_routes2()
   RETURNS character varying AS
$BODY$
DECLARE

   cur_pupil refcursor;
   v_pid integer;
   v_seid integer;
   v_spos float8;
   v_teid integer;
   v_tpos float8;
   v_geom geometry;
   v_sql varchar(1000);

BEGIN
   OPEN cur_pupil FOR EXECUTE format('SELECT pupilid, source_eid, source_pos, target_eid, target_pos FROM edn_pupilschoolroute WHERE pupil_nn IS NOT NULL LIMIT 1000');
   LOOP
   FETCH cur_pupil INTO v_pid, v_seid, v_spos, v_teid, v_tpos;
   EXIT WHEN NOT FOUND;
   RAISE NOTICE 'Processing pupil % journey...', v_pid;
   WITH results AS (
   SELECT d.seq, d.id1 AS _node, d.id2 AS _edge, cost, r.centrelinegeometry AS geometry FROM pgr_trsp('
         SELECT ogc_fid AS id,
           source::integer,
           target::integer,
           cost_len::double precision AS cost,
           rcost_len::double precision AS reverse_cost
         FROM hw_roadlink'::text, -- the trsp route
         v_seid, --pupil source edge id
         v_spos, --source edge position
         v_teid, --school target edge id
         v_tpos, --target edge position
         true, --directed
         true, --reverse costs
         'select to_cost, teid as target_id, feid||coalesce('',''||via,'''') as via_path from hw_nt_restrictions'::text) AS d
   INNER JOIN hw_roadlink r ON d.id2 = r.ogc_fid
   ORDER BY d.seq),
   max_seq AS (
    SELECT max(seq) AS max_seq FROM results
    ),
   network AS
    (
     SELECT ogc_fid AS id, source, target FROM hw_roadlink a, results WHERE a.ogc_fid = results._edge
    ),
   path_geom AS
    (
   (SELECT ST_LineSubstring(geometry,v_spos,1.0) AS geometry -- source edge and first row
    FROM results, network
     WHERE seq = (SELECT min(seq) FROM results)
     AND network.target = (SELECT _node FROM results WHERE seq = 1)
     AND network.id<http://network.id> = (SELECT _edge FROM results WHERE seq = 0)
    UNION
   SELECT ST_LineSubstring(ST_Reverse(geometry),v_spos,1.0) AS geometry -- source edge and first row
    FROM results, network
     WHERE seq = (SELECT min(seq) FROM results)
     AND network.source = (SELECT _node FROM results WHERE seq = 1)
     AND network.id<http://network.id> = (SELECT _edge FROM results WHERE seq = 0)
   )
    UNION
   (SELECT ST_LineSubstring(geometry,0.0,1.0 - v_tpos) AS geometry -- target edge and last row
    FROM results, network
     WHERE seq = (SELECT max(seq) FROM results)
     AND network.source = (SELECT _node FROM results, max_seq WHERE seq = max_seq)
     AND network.id<http://network.id> = (SELECT _edge FROM results, max_seq WHERE seq = max_seq)
    UNION
   SELECT ST_LineSubstring(ST_Reverse(geometry),0.0,1.0 - v_tpos) AS geometry -- target edge and last row
   FROM results, network
    WHERE seq = (SELECT max(seq) FROM results)
     AND network.target = (SELECT _node FROM results, max_seq WHERE seq = max_seq)
     AND network.id<http://network.id> = (SELECT _edge FROM results, max_seq WHERE seq = max_seq)
   )
    UNION
   SELECT geometry -- intermediate edges and rows
   FROM results WHERE seq NOT IN ((SELECT max(seq) FROM results),(SELECT min(seq) FROM results))
  )
SELECT ST_Multi(ST_Union(geometry)) AS geometry FROM path_geom INTO v_geom;

   -- insert route cost into pupil data table
   EXECUTE format('INSERT INTO %s(pupilid,geometry) VALUES ($1,$2)','corporate.edn_pupilroutes2')
     USING v_pid, v_geom;

   END LOOP;
   RETURN 'Oooh, get in!';
   CLOSE cur_pupil;
END;
$BODY$
   LANGUAGE plpgsql VOLATILE
   COST 100;






-----Original Message-----
From: Pgrouting-users [mailto:pgrouting-users-bounces at lists.osgeo.org<mailto:pgrouting-users-bounces at lists.osgeo.org>] On Behalf Of Stephen Woodbridge
Sent: 24 April 2017 15:23
To: pgrouting-users at lists.osgeo.org<mailto:pgrouting-users at lists.osgeo.org>
Subject: Re: [pgrouting-users] best/fastest way to calculate thousands of trsp routes

On 4/24/2017 4:55 AM, McDonaldR wrote:
Thanks Steve

The function to get the source and target points on to the nearest
edges gives a much better result than using nearest node.  Now I just
need to work out how to get the geometry of the route from these
projected points.

For the first and last edgeid in the result, use the linear referencing functions to split that edge and keep the part you need instead of the whole thing. the "pos" can be used as the split location on the edge.

-Steve
Thanks very much for the help

Ross

-----Original Message----- From: Pgrouting-users
[mailto:pgrouting-users-bounces at lists.osgeo.org<mailto:pgrouting-users-bounces at lists.osgeo.org>] On Behalf Of Stephen
Woodbridge Sent: 20 April 2017 16:50 To:
pgrouting-users at lists.osgeo.org<mailto:pgrouting-users at lists.osgeo.org> Subject: Re: [pgrouting-users]
best/fastest way to calculate thousands of trsp routes

On 4/20/2017 6:49 AM, McDonaldR wrote:
Hi List,

I’m running pgRouting 2.1 with PostGIS 2.2.2 on PostgreSQL 9.2.20.

I have 16,000 pupils going to 57 schools.  I have a network with turn
restrictions.  I have a function (below) that loops through all the
pupils and calculates a TRSP route and updates the pupil table with
the route cost.  I have some questions too.

1.It’s going to take ~ 2 hours to process all the pupils.  Will it
make things faster if I created, say, 4 functions that each processed
a different set of pupils?  I have a multicore server and memory to
spare. I have to run this for time and distance and also for all the
pupils assigned an “optimally located” school. What’s the
best/fastest way to do this?

Yes, this sounds reasonable.
2.I pre-processed the pupil data to assign each pupil the nearest
node on the network. Some pupils in rural areas are a mile from the
nearest node and are assigned the node at the end furthest from the
school. How would I use the pgr_trsp with edges and edge position to
create a position for each pupil at a point on the nearest edge?

Here is a function that might be useful, or you might modify it for
your specific needs. tol is maximum search distance in degrees, you
can estimate this degrees = meters/111120.0. It returns the edge_id,
pos on the that edge and these can be used to args to trsp.

-Steve W

create or replace function pointToEdgePos(edge_table text, lon float8,
lat float8, tol float8, OUT edge_id integer, OUT pos float8) returns
record as $body$ -- ASSUMPTIONS -- * edge_table as columns "gid" and
"geom" -- * edge_able.geom uses srid=4326 declare rr record; pct
float8; pnt geometry; geom geometry;

begin -- create a point from lon, lat pnt :=
st_setsrid(st_makepoint(lon,lat), 4326);

-- set the error condition edge_id := null; pos := -1.0;

-- find the closest edge within tol distance execute 'select * from '
|| _pgr_quote_ident(edge_table) || ' where st_dwithin(''' ||
pnt::text || '''::geometry, geom, ' || tol || ') order by
st_distance(''' || pnt::text || '''::geometry, geom) asc limit 1'
into rr;

if rr.geom is not null then -- deal with MULTILINESTRINGS geom :=
rr.geom; if geometrytype(geom)='MULTILINESTRING' THEN geom :=
ST_GeometryN(geom, 1); end if;

-- project the point onto the linestring pos :=
st_line_locate_point(geom, pnt); edge_id := rr.gid; end if;

end; $body$ language plpgsql stable;

CREATE OR REPLACE FUNCTION public.pupil_journeys()

RETURNS character varying AS

$BODY$

DECLARE

cur_pupil refcursor;

v_pid integer;

v_pnn integer;

v_snn integer;

v_cost double precision;

v_sql varchar(1000);

BEGIN

RAISE NOTICE 'Processing pupil journeys...';

OPEN cur_pupil FOR EXECUTE format('SELECT pupilid, pupil_nn,
school_nn FROM edn_pupilschoolroute WHERE pupil_NN IS NOT NULL');

LOOP

FETCH cur_pupil INTO v_pid, v_pnn, v_snn;

EXIT WHEN NOT FOUND;

SELECT SUM(cost) AS v_cost FROM pgr_trsp('

SELECT ogc_fid AS id,

source::integer,

target::integer,

cost_len::double precision AS cost,

rcost_len::double precision AS reverse_cost

FROM hw_roadlink'::text,

v_pnn, --pupil_nn gets inserted here

v_snn, --school_nn gets inserted here

true,

true,

'select to_cost, teid as target_id, feid||coalesce('',''||via,'''')
as via_path from hw_nt_restrictions'::text) INTO v_cost;

-- insert route cost into pupil data table

v_sql:='UPDATE edn_pupilschoolroute SET p_dist = ' || v_cost || '
WHERE pupil_nn = ' || v_pnn || ' AND school_nn = ' || v_snn || '
AND pupilid = ' || v_pid;

EXECUTE v_sql;

END LOOP;

RETURN ‘Well, that worked!';

CLOSE cur_pupil;

END;

$BODY$

LANGUAGE plpgsql VOLATILE

COST 100;

Thanks in advance

Ross

*Ross McDonald | *GIS Data Coordinator | Angus Council | Angus House,
Orchardbank Business Park, Sylvie Way, Forfar DD8 1AT*| t:
01307 476419*

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