[pgrouting-users] Build the "right" direction in a network, from a fixed starting point

[andy]

Hi Vicky,
you are right. Below my steps.

In you example you create a table with the geometric and cost infos for
every edge.
Instead I import a shapefile that have inside the right directions of the
edges (but not the cost), and I want to use these directions to calculate
if it’s possible to go in example from point A to point N.
Than I think that before to use pgr_createTopology and pgr_dijkstra, I must
calculate the cost outside pg_routing. Am I right?

These are my steps:

   - I import a shapefile (I’m attaching it) with ogr2ogr -overwrite -lco
   LAUNDER=No -f PostgreSQL PG:"dbname=mydb host=localhost port=5432
   user=myuser password=mypassword" "linee.shp" -nln "linee";
   - then I run

ALTER TABLE linee ADD source INT4;ALTER TABLE linee ADD target
INT4;select pgr_createTopology('linee',
0.000001,the_geom:='wkb_geometry',id:='ogc_fid');


   - and finally

SELECT * FROM pgr_dijkstra('SELECT ogc_fid as id, source, target,
st_length(wkb_geometry)
                           as "cost" FROM linee',1,ARRAY[2,3,4,5,6])

It gives me in output the table below:
seq path_seq end_vid node edge cost agg_cost
1 1 2 1 1 1875.887941 0.0
2 2 2 2 -1 0.0 1875.887941
3 1 4 1 3 1506.74402482 0.0
4 2 4 4 -1 0.0 1506.74402482
5 1 5 1 3 1506.74402482 0.0
6 2 5 4 4 1208.08883443 1506.74402482
7 3 5 5 -1 0.0 2714.83285924
8 1 6 1 1 1875.887941 0.0
9 2 6 2 5 1447.12212188 1875.887941
10 3 6 6 -1 0.0 3323.01006288

I need way to have that it’s impossible to go from 1 to 3, because the edge
2 has direction that blocks it.

Thank you very much, especially for your patience

[image: immagine.png]
​
-- 
___________________

Andrea Borruso
website: https://medium.com/tantotanto
38° 7' 48" N, 13° 21' 9" E, EPSG:4326
___________________

"cercare e saper riconoscere chi e cosa,
 in mezzo all’inferno, non è inferno,
e farlo durare, e dargli spazio"

Italo Calvino
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