[pgrouting-users] best/fastest way to calculate thousands of trsp routes
McDonaldR
McDonaldR at angus.gov.uk
Tue Apr 25 09:15:48 PDT 2017
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 = (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 = (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 = (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 = (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] On Behalf Of Stephen Woodbridge
Sent: 24 April 2017 15:23
To: 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] On Behalf Of Stephen
> Woodbridge Sent: 20 April 2017 16:50 To:
> 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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>>
>>
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>
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