How to convert SHP/POSTGIS data into x, y, z, “cost” data?

Question

Is there a way to convert a line layer (shp or PostGIS) data into (x, y , z, cost) i.e. (From_node, To_node, optional_Elevation, Cost/Weight) ?

Answer 1

Some additional information would be useful to find out exactly how your data looks like and what you are trying to get out of it. The following statement might be a start:

SELECT startpoint(the_geom), endpoint(the_geom), z(endpoint(the_geom)), 
length(the_geom) FROM test_lines;

I didn't know where you want the elevation to be measured, so I took the z value at the end point for now.

Update Jul 31:

SELECT startpoint(the_geom), endpoint(the_geom), elevation, cost 
FROM test_lines;

Update Aug 1:

In OGR, a LineString object has similar functions StartPoint() and EndPoint().