[pgrouting-users] TSP and how to contribute

[Daniel Kastl]

2011/1/14 Emre Koc <emrekoch at gmail.com>

>
> /emre
>
>
> On Fri, Jan 14, 2011 at 10:15 AM, Daniel Kastl <daniel at georepublic.de>wrote:
>
>>
>>
>> 2011/1/14 Emre Koc <emrekoch at gmail.com>
>>
>> Sure
>>>
>>> Here is my sql query for that image.
>>>
>>> SELECT edges.gid, ST_AsText(edges.the_geom) AS geotext,
>>>                  edges.ft_minutes,
>>>  edges.meters
>>> FROM edges,
>>> (SELECT edge_id, cost FROM driving_distance('SELECT gid as id,
>>>  source::integer,
>>>  target::integer,
>>>          meters::double precision as cost
>>>  FROM edges', $startVertexID, $cost,false,false)
>>> )  as rt
>>> WHERE edges.gid=rt.edge_id;";
>>>
>>> I just give a sample vertex id and a cost value in meters and got
>>> resulting edges. Normally when I find shortest paths all roads are connected
>>> so the graph is ok. But this driving directions does not output connected
>>> roads, thats the thing I do not understand.
>>>
>>
>> Driving distance returns you all the vertices you can reach from a start
>> point to within what you have defined as the maximum costs.
>> I think you're looking for another query (Dijkstra, A-Star, Shooting
>> Star).
>>
>
> I am looking for a output that shows road network that I can reach from a
> start point within a defined maximum cost. So if driving distance does not
> output connected edges what do you suggest me to do in order to have a
> connected road network with the given vertices ? Running shortest path for
> each vertex does not seem feasible but I am unable to see a way to implement
> it without going inside c functions.
>
>
Sorry, I was wrong ... it's the right function you're using. Somehow read
driving directions somewhere before.
Driving directions does what you need, except that it returns you a list of
vertices you can reach and the edges column doesn't return anything useful.

This custom wrapper function takes the vertices and calculates a polygon
that contains all of them:
https://github.com/pgRouting/pgrouting/blob/master/extra/driving_distance/sql/routing_dd_wrappers.sql#L78

Daniel






-- 
Georepublic UG & Georepublic Japan
eMail: daniel.kastl at georepublic.de
Web: http://georepublic.de
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