[pgrouting-dev] Building some tools to work with TSP
Helder Alves
helderalvespt at gmail.com
Mon Nov 4 08:31:25 PST 2013
Hi Steve,
select dmatrix::float8[]
> from pgr_vidstodmatrix(
> pgr_pointstovids(
>
> pgr_texttopoints('-7.50501,40.26310;-7.48864,40.17530;-7.49901,40.13950;-7.57596,40.12350;-7.61591,40.13230;-7.61935,40.13230;-7.67235,40.13580;-7.67087,40.13660;-7.66510,40.13860;-7.74559,40.15640;-7.74588,40.15730;-7.74746,40.15690;-7.74922,40.15540;-7.74926,40.15310;-7.73537,40.14230;-7.63556,40.18920;-7.64849,40.22630;-7.62354,40.25680;-7.62425,40.26280;-7.62223,40.25830;-7.62179,40.25680;-7.62116,40.25580;-7.64803,40.22390;-7.63916,40.20560;-7.63664,40.20250;-7.63767,40.19970;-7.63623,40.20000;-7.56974,40.26710;-7.49104,40.26500;-7.50473,40.26320',
> 4326),
> 'ways'),
>
> pgr_texttopoints('-7.50501,40.26310;-7.48864,40.17530;-7.49901,40.13950;-7.57596,40.12350;-7.61591,40.13230;-7.61935,40.13230;-7.67235,40.13580;-7.67087,40.13660;-7.66510,40.13860;-7.74559,40.15640;-7.74588,40.15730;-7.74746,40.15690;-7.74922,40.15540;-7.74926,40.15310;-7.73537,40.14230;-7.63556,40.18920;-7.64849,40.22630;-7.62354,40.25680;-7.62425,40.26280;-7.62223,40.25830;-7.62179,40.25680;-7.62116,40.25580;-7.64803,40.22390;-7.63916,40.20560;-7.63664,40.20250;-7.63767,40.19970;-7.63623,40.20000;-7.56974,40.26710;-7.49104,40.26500;-7.50473,40.26320',
> 4326),
> 'ways')
While running the query above, I got the error below.
column "id" does not exist
> LINE 1: select id, source, target, cost from ways where the_geom && ...
> ^
> QUERY: select id, source, target, cost from ways where the_geom &&
> '0103000020E610000001000000050000002E34D769A4651FC05EBA490C020344402E34D769A4651FC0492EFF21FD2E444076ABE7A4F78D1DC0492EFF21FD2E444076ABE7A4F78D1DC05EBA490C020344402E34D769A4651FC05EBA490C02034440'::geometry
> CONTEXT: PL/pgSQL function
> pgr_vidstodmatrix(integer[],geometry[],text,double precision) line 57 at
> FOR over EXECUTE statement
I guess it's some kind of bug, which is something it may happen when we are
testing something from the develop branch! :-)
Can you help me with this?
Thanks!
--
Helder Alves
+351912384076
On Wed, Oct 9, 2013 at 5:26 PM, Stephen Woodbridge
<woodbri at swoodbridge.com>wrote:
> Another common problem is orienting the returned edges so they match up
> end to end. For example:
>
> select st_astext(the_geom) from pgr_tsptrsp(pgr_texttopoints('
> 2,0;2,1;3,1;2,2;4,1;4,2;2,3;3,2', 0), 'edge_table', true, true) a,
> edge_table b where a.id2=b.id;
>
> "LINESTRING(2 1,2 2)"
> "LINESTRING(2 2,3 2)"
> "LINESTRING(3 2,4 2)"
> "LINESTRING(4 1,4 2)" -- needs to be flipped
> "LINESTRING(3 1,4 1)" -- needs to be flipped
> "LINESTRING(2 1,3 1)" -- needs to be flipped
> "LINESTRING(2 1,2 2)"
> "LINESTRING(2 2,2 3)"
> "LINESTRING(2 2,2 3)" -- needs to be flipped
> "LINESTRING(2 1,2 2)" -- needs to be flipped
> "LINESTRING(2 0,2 1)" -- needs to be flipped
> "LINESTRING(2 0,2 1)"
>
> So I wrote a new function pgr_flipedges(ga geometry[]) that can be used
> like this:
>
> select st_astext(e) from (
> select unnest(pgr_flipedges(array_agg(the_geom))) as e
> from pgr_tsptrsp(pgr_texttopoints('2,0;2,1;3,1;2,2;4,1;4,2;2,3;3,2',
> 0), 'edge_table', true, true) a,
> edge_table b
> where a.id2=b.id
> ) as foo;
>
> "LINESTRING(2 1,2 2)"
> "LINESTRING(2 2,3 2)"
> "LINESTRING(3 2,4 2)"
> "LINESTRING(4 2,4 1)"
> "LINESTRING(4 1,3 1)"
> "LINESTRING(3 1,2 1)"
> "LINESTRING(2 1,2 2)"
> "LINESTRING(2 2,2 3)"
> "LINESTRING(2 3,2 2)"
> "LINESTRING(2 2,2 1)"
> "LINESTRING(2 1,2 0)"
> "LINESTRING(2 0,2 1)"
>
> Notice how all the edges have been flipped to return a continuous path
> from start to end of each adjacent segment in the path.
>
> -Steve
> All the mentioned code will eventually get checked into pgrouting 2.1
> development branch once it is stable and I have test cases and docs written
> for it.
>
> -Steve
>
>
> On 10/9/2013 10:29 AM, Stephen Woodbridge wrote:
>
>> Hi all,
>>
>> I have been playing with some tools to allow me to integrate TSP
>> optimization into a web application. I thought I would share what I have
>> come up with for comments. One of the things I did was to try and break
>> down the process into reusable modular functions. For example there are
>> two functions to compute the distance matrix based on either Euclidean
>> or kdijkstra distances. One could add other functions to compute them
>> based on other algorithms. Also each function does one conversion so it
>> is simple to understand and easy to test or replace with another
>> function that does the transformation in a different way. Then the final
>> function glues all the pieces together to get the final result.
>>
>> Goal:
>>
>> take a string or points like "x,y;x,y;x,y;..." and compute the TSP
>> solution to order the points based on either Euclidean distance or
>> network distances, then compute the route through the network and return
>> the route geometry.
>>
>> Solution in progress:
>>
>> 1. text to point geometry *
>> pgr_texttopoints(pnts text, srid integer DEFAULT(4326))
>>
>> 2. points to vertex ids *
>> pgr_pointtoedgenode(edges text, pnt geometry, tol float8)
>> pgr_pointstovids(pnts geometry[], edges text, tol float8
>> DEFAULT(0.01))
>>
>> 3. points to edge ids **
>>
>> 4. points to [edge id, pct] **
>>
>> 5. points to Euclidean distance matrix *
>> pgr_points2dmatrix(pnts geometry[], OUT dmatrix double precision[],
>> OUT ids integer[])
>>
>> 6. vertex ids to kdijkstra distance matrix *
>> pgr_vidstodmatrix(IN vids integer[], IN pnts geometry[], IN edges
>> text, tol float8 DEFAULT(0.1), OUT dmatrix double precision[], OUT ids
>> integer[])
>>
>> 7. distance matrix to TSP to ordered list ***
>> select * from pgr_tsp(
>> (select dmatrix::float8[]
>> from pgr_vidstodmatrix(
>> pgr_pointstovids(
>> pgr_texttopoints('2,0;2,1;3,1;2,2;4,1;4,2;2,3;3,2',
>> 0),
>> 'edge_table'),
>> pgr_texttopoints('2,0;2,1;3,1;2,2;4,1;4,2;2,3;3,2', 0),
>> 'edge_table')
>> ),
>> 1
>> );
>>
>> 8. reorder vids based on ordered list *
>>
>> 9. compute trsp for pairs of vids in ordered list *,!
>> pgr_trsp(sql text, vids integer[], directed boolean,
>> has_reverse_cost boolean, turn_restrict_sql text DEFAULT NULL::text)
>>
>> pgr_tsptrsp(pnts geometry[], edges text, directed boolean,
>> has_reverse_cost boolean, tol float8 DEFAULT(0.1), turn_restrict_sql
>> text DEFAULT NULL::text)
>>
>> select * from
>> pgr_tsptrsp(pgr_texttopoints('2,0;2,1;3,1;2,2;4,1;4,2;2,3;3,2', 0),
>> 'edge_table', true, true);
>>
>>
>> 10. output results **
>>
>> NOTES:
>> * - done
>> ** - not done
>> *** - already part of 2.0
>> ! - computing a route through via points can be optimized in the C/C++
>> code for better performance, but I currently just prototyped this up in
>> plpgsql
>>
>> Thoughts,
>> -Steve
>> _______________________________________________
>> pgrouting-dev mailing list
>> pgrouting-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/pgrouting-dev
>>
>
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