[pgrouting-users] Wierd results using pgr_kdijkstraPath

Thu Dec 18 07:17:20 PST 2014

And here I enclose below the resulted travel_costs’ table of pgr_dijkstra function:

Note that Shortest path cost on original network (between the 2 lines of the resulted vector feature) is around 250m (below - by converting from millimeter to meter) whereas the sum of costs in the above table is around 45m only

Thanks..

Eyad

From: AUS - Eyad [mailto:b00038807 at aus.edu] 
Sent: Thursday, December 18, 2014 7:02 PM
To: 'pgRouting users mailing list'
Subject: RE: [pgrouting-users] Wierd results using pgr_kdijkstraPath

Here is a prt_sc after trying pgr_dijkstra as follows:

SELECT seq, id1 as path, (b.geom) as geom, cost FROM pgr_dijkstra(

    'SELECT id, source, target, (st_length(geom) * 0.001) as cost FROM schema.network_noded',

    336, (SELECT MAX(id) FROM schema.l1_pv1), false, false

  ) a, schema.network_noded b 

WHERE a.id1=b.id

As you may see, there is only too little parts of the network’s lines left (on the sides of the layout)! No route is visible

Hope this clarifies..

Eyad

From: AUS - Eyad [mailto:b00038807 at aus.edu] 
Sent: Thursday, December 18, 2014 6:29 PM
To: 'pgRouting users mailing list'
Subject: RE: [pgrouting-users] Wierd results using pgr_kdijkstraPath

Hi Daniel,

Enclosed are 3 maps (1st prt_sc with the original network, 2nd & 3rd prt_sc with the resulted network)

Clearly, the majority of the network has faded away

Awaiting your feedback, I would work on 2nd suggestion

Regards,

Eyad

From: pgrouting-users-bounces at lists.osgeo.org [mailto:pgrouting-users-bounces at lists.osgeo.org] On Behalf Of Daniel Kastl
Sent: Thursday, December 18, 2014 6:28 AM
To: pgRouting users mailing list
Subject: Re: [pgrouting-users] Wierd results using pgr_kdijkstraPath

Hi Eyad,

It's difficult to give an answer based on your query and problem description only. I guess, that (still) your network topology is not correct. It looks like a data problem.

There are 2 things you could do for now:

(1) Show us some image of your "weird de-attached “little” pieces"

(2) Try a simple shortest path query with one start and one end point and see if it works with pgr_dijkstra function for example.

Daniel

On Thu, Dec 18, 2014 at 7:37 AM, AUS - Eyad <b00038807 at aus.edu> wrote:

Hello pgr_Experts,

I’m trying to get all the routes from a source point (i.e. 336) to a group of target/destination points (located at different edges/ends of linestrings’ network) using the below code:

SELECT seq, id1 as path, id2 as node, id3 as edge, (b.geom) as geom, cost FROM pgr_kdijkstraPath(

    'SELECT id, source, target, (st_length(geom) * 0.001) as cost FROM schema.network_noded',

    336, (SELECT array_agg(id) FROM schema.l1_pv1), false, false

  ) a, schema.network_noded b 

WHERE a.id1=b.id

It’s resulting a weird de-attached “little” pieces of my original nodded_network! However, the number of resulted paths is equal to the target/destination points. Please advise:

1)      What potential mistake I may have committed?

2)      Does it mean that all the calculated travel_cost(s) are wrong (as they are reflected/represented by wrong linestrings)?

I'm using QGIS 2.4.0 and pgRouting pg93-binaries-2.4.0

I found similar question on this list of pgRouting users, asked by Antonio last October (http://lists.osgeo.org/pipermail/pgrouting-users/2014-October/001992.html ), but obviously the question is not answered yet?

Regards..

Eyad

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