[pgrouting-users] FW: Multiple queries in a row

Thu Nov 22 02:47:33 PST 2012

Could you explain me how to build "pgrouting" github project? I have no experience with cmake tool.
Thanks!

From: daniel at georepublic.de
Date: Wed, 21 Nov 2012 22:44:13 +0900
To: pgrouting-users at lists.osgeo.org
Subject: Re: [pgrouting-users] FW: Multiple queries in a row

Sorry, the Wiki page says you need it.But for DD (driving Distance) you need to install (compile) GAUL.
Daniel

On Wed, Nov 21, 2012 at 10:40 PM, Daniel Kastl <daniel at georepublic.de> wrote:

On Wed, Nov 21, 2012 at 10:15 PM, Iñigo Vázquez <ivgwildchild666 at hotmail.com> wrote:

Nice! I think this should be valid for my case. But I'm having some troubles in compilation/installation.I've downloaded the .zip archive from github and I extracted it. From "cmake" folder I execute this command "cmake -DWITH_DD=ON" and then, when I try to execute this one "sudo make install"  isn't work (there's no rule for install target).

Am I doing something wrong?

Well, that's hard to tell without more details about the error and your OS, etc.. 

But have you tried without "-DWITH_DD=ON"? Do you need it?
Daniel 

From: daniel at georepublic.de
Date: Wed, 21 Nov 2012 20:39:59 +0900
To: pgrouting-users at lists.osgeo.org

Subject: Re: [pgrouting-users] FW: Multiple queries in a row

There is something, but it didn't make it yet into pgRouting master branch:https://github.com/pgRouting/pgrouting/wiki/APSP

You can find it in this branch:

https://github.com/pgRouting/pgrouting/tree/gsoc-tdsp
Daniel

On Wed, Nov 21, 2012 at 8:05 PM, Tao Romera Martinez <taoromera at gmail.com> wrote:

Hi Iñigo,
I needed to do something similar to what you are trying to do some time ago and asked in the list. Unfortunately, it is not possible to retrieve several shortest paths in one run. It is certainly possible to reduce the time needed to perform the shortest path routing between a set of nodes, but for this the code of the shortest_path C function should be modified to fetch the road network data it needs from the DB only once and then perform the routing algorithm several times. 

Tao

2012/11/21 Iñigo Vázquez <ivgwildchild666 at hotmail.com>

Thanks for your reply, but in my case the shortest path doesn`t interest me. I need the shortest paths from one given node to each others beacuse then I want to calculate a path taking into account a given time limit. 

Something like in the "Traveling Salesman Problem" but with Time Window.
Thanks!

From: gunnar at tradlosetrondheim.no
Date: Wed, 21 Nov 2012 11:08:03 +0100
Subject: Re: [pgrouting-users] Multiple queries in a row
To: pgrouting-users at lists.osgeo.org

CC: ivgwildchild666 at hotmail.com

Hello,

I do not know the answer to you question, but I might know an workarround if you are only interrested in the shortest of them.

We use a hack to find the path to the closest node of a set of nodes.

Basically we tweak the query which builds the graph to rename all nodes which are applicable to some id which cannot be found in the graph elsewere (e.g. -1), and the search for the path to this node.

(NB: this could/would give strange beahviour if used with astar)

Best regards Gunnar

2012/11/21 Iñigo Vázquez <ivgwildchild666 at hotmail.com>

Dear all,

I need to obtain a set of nearest nodes from a given location (maybe 30 or 40). Then I need to calculate the shortest path from the given node from each others. It means to execute shortes_path query multiple times in a row, wich takes about 2 seconds (1 query 2 seconds: 30 queries 60 -> too long).

SELECT * FROM shortest_path('
   SELECT id AS id,
          source::int4 AS source,
          target::int4 AS target,
          cost::float8 AS cost
   FROM tt_2po_4pgr',
275742,
274494,
false,
false)

What would be the best way to do this in a reasonable time?

Thank in advance!

Pd: excuse my english 		 	   		  

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    Gunnar Rangøy

    System developer

    Trådløse Trondheim / Wireless Trondheim

    tradlosetrondheim.no

    +47 99 36 06 99

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