Vilem Ded wrote > Hi, > I have set of points with attribute table (let just say with column "A" > containing 1s and 2s). > I would love to use function v.hull in order to get two convex hulls > (their > faces). Basically apply function "by group". Unfortunatelly, I was not > able > to find simple way to do that. > > First solution I came up with was scripting with for cycle using > "category" > - picking ids of points and then run: > v.hull input=mypoints output=myhulls1 cat="1,3,40,etc" > v.hull input=mypoints output=myhulls2 cat="2,4,41,etc" > > Than I tried where clause: > v.hull input=mypoints output=myhulls1 where="A<2" > v.hull input=mypoints output=myhulls2 where="A>1" > > Unfortunatelly, this clumsy solution (I have hounderds thousands of point > sets) does not work. All four lines gave me the same result (convex hull > created from all points). > The only even more clumsy solution I succeded with was first use > 'v.extract' > and than apply 'v.hull' on newly created maps. > > My questions: > Is there a way how to effectively apply function(command) by group? > Is the v.hull function supposed to work like this (ingnoring where and cat > arguments)?
confirmed that where or cat seems not to work. please open a ticket for this. ----- best regards Helmut -- Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html _______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user
