[postgis-users] help with a query

[Sufficool, Stanley]

Create a view without the road type = 22 and use that in
dijkstra_sp_directed() ?

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net 
> [mailto:postgis-users-bounces at postgis.refractions.net] On 
> Behalf Of Pedro Doria Meunier
> Sent: Tuesday, November 25, 2008 6:52 AM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] help with a query
> 
> 
> Hi Fred,
> 
> Thanks for taking an interest :)
> 
> Well ... I'd already done it for the one-way streets.
> There are 2 scenarios here:
> - vehicle routes
> - pedestrian routes
> 
> So when I'm trying to calculate a route for a vehicle I don't 
> want the 
> algorithm to include road_type=22.
> 
> Whenever I decide to calculate a pedestrian route it must 
> return all of 
> the possible segments.
> 
> The wrappers themselves don't allow you to do that ...
> 
> BR,
> Pedro Doria Meunier
> 
> Fred Lehodey wrote:
> > Hi Pedro,
> > you are calculating the route with all roads and only after you are
> > filtering with the WHERE clause.
> >
> > IMO, better is to create a field with high costs (Ex:10000) to roads
> > when road_type=22 and length for road_type != 22.
> > After that, you can run the function shortest_path() using your new 
> > cost field.
> >
> >
> > Fred.
> >
> >
> > On Tue, Nov 25, 2008 at 2:16 AM, Pedro Doria Meunier
> > <pdoria at netmadeira.com <mailto:pdoria at netmadeira.com>> wrote:
> >
> >     Hi guys :) -- a *special* wink to David Techer ;-)
> >
> >     I'm having a bit of trouble figuring out what can I do with the
> >     wrapper functions of pgRouting... (blush)
> >
> >     The thing is:
> >
> >     I have everything perfectly in place, pgRouting working as it's
> >     supposed to, but!
> >
> >     I have a dataset that describes the road type. I want to filter
> >     the results provided by pgRouting in a way that it *doesn't*
> >     return return pedestrian segments (btw: road_type=22).
> >
> >     So, as to the query itself (basic) 1st try:
> >
> >     SELECT gid, AsBinary(the_geom) AS the_geom
> >       FROM dijkstra_sp_directed('pt_madeira_roads', 11780, 
> 424, true,
> >     true);
> >
> >     Works like a charm except that it returns pedestrian 
> segments (of
> >     course).
> >
> >     2nd try:
> >
> >     SELECT rt.gid, AsText(rt.the_geom) AS wkt,
> >                      length(rt.the_geom) AS length, roads.gid
> >                   FROM my_roads as roads,
> >                       (SELECT gid, the_geom
> >                           FROM dijkstra_sp_directed(
> >                               'my_roads',
> >                               11780,
> >                               424,
> >                               true,true)
> >                        ) as rt
> >                   WHERE roads.road_type<>22 and roads.gid=rt.gid;
> >
> >     Leaves me with *holes* in the route.
> >
> >     All of this is, of course, a consequence of my own stupidity and
> >     late hours but I'd surely appreciate if some brave soul 
> could look
> >     into it. ;-)
> >
> >     Already thankful in advance,
> >     Pedro Doria Meunier.
> >
> >
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> >
> >
> > 
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