[GRASS-user] grass

[ec.jkd at tpcsed.com]

hi,
 After executing the following steps for shortest path in grass i get below error:
echo "update roads set travelcost=5 where cat=1" | db.execute
echo "update roads set travelcost=20 where cat=2" | db.execute
echo "update roads set travelcost=40 where cat=3" | db.execute
echo "update roads set travelcost=60 where cat=4" | db.execute
echo "update roads set travelcost=80 where cat=5" | db.execute
echo "select * from roads" | db.select

Then we can run the 'd.path' with our assigned travel costs:

d.path map=roads afcol=travelcost abcol=travelcost

error:Building graph:
ERROR: Column type not supported

Can anyone help me out with this