How is the column "cost" and similars calculated?

[Doev]

Hello,

first: I do not feel well with starting this question as an issue. Is there any forum, that I can use for asking common questions?

How are the columns "cost" and "cost_s" calculated? I don't see any hint in the "mapconfig.xml".

[dkastl]

The following "channels" are available to ask questions: http://pgrouting.org/support.html
The Gitter channel is in general a good place: https://gitter.im/pgRouting/pgrouting

[dkastl]

I agree that a bit more documentation might be good to have.
However, the formula is available in this SQL:

osm2pgrouting/src/database/Export2DB.cpp

Lines 370 to 380 in 2adbbf3

	" UPDATE " + table +
	" SET length_m = ST_length(geography(ST_Transform(the_geom, 4326))),"
	" cost_s = CASE "
	" WHEN one_way = -1 THEN -ST_length(geography(ST_Transform(the_geom, 4326))) / (maxspeed_forward::float * 5.0 / 18.0)"
	" ELSE ST_length(geography(ST_Transform(the_geom, 4326))) / (maxspeed_backward::float * 5.0 / 18.0)"
	" END, "
	" reverse_cost_s = CASE "
	" WHEN one_way = 1 THEN -ST_length(geography(ST_Transform(the_geom, 4326))) / (maxspeed_backward::float * 5.0 / 18.0)"
	" ELSE ST_length(geography(ST_Transform(the_geom, 4326))) / (maxspeed_backward::float * 5.0 / 18.0)"
	" END "
	" WHERE length_m IS NULL AND maxspeed_backward !=0 AND maxspeed_forward != 0;");

Maybe it would be better to leave the cost computation to the user, as also discussed recently here: #275 (comment)

[Doev]

Good morning Daniel,

thank you for your info. I didn't see that osm2pgrouting is an official pgrouting project and the theire channels can be used. Next time I will use it.

[bawidyantoro]

Dear dkastl

what the meaning og (maxspeed_backward::float * 5.0 / 18.0)? can I modify it as neede in osm2pgrouting?

[Doev]

bawidyantoro, it's just sql-code. You can execute it later in your database. But you have to modify the WHERE part, cause it only updates the fields that contains NULL.

In your case, I would take a look to the file that Daniel pointed to: osm2pgrouting/src/database/Export2DB.cpp