Many thanks Markus... I did this way (for a line only, which has category=163 ... now I will create a cycle for each line of the map):
with this I obtain the length of the line subtracted of 20 meters: echo "`v.report map=Reticol layer=1 option=area units=meters | grep 163 | cut -f3 -d'|'`-20" | bc -l with this I create a segment which is 40 meters shorter than the previous one (20 meters from each node): echo "L 1 163 20 3434.21" | v.segment input=Reticolo_050407_LAST output=prova but no way to do v.overlay with two lines, so I create a buffer of 1 centimeter around the line: v.buffer input=prova output=prova_buf type=line layer=1 buffer=0.01 scale=1.0 tolerance=0.01 then I will put all the buffers into a single map (v.patch) and at the end: v.overlay to obtain the lines network cutted of 20 meters at each node... Grazie... Ivan Il giorno dom, 08/07/2007 alle 12.27 -0700, Markus Neteler ha scritto: > > ivan marchesini wrote: > > > > Dear Users... > > I have a vector lines map... > > I would like to shorten each line of the map.... the amount of the > > shortening could be fixed (10 meters.. may be) > > I would like to do this in each part of the line... i.e.: > > > > old lines: > > ____________ > > > > new lines: > > __________ > > > > > > any idea about a quick way to solve this problem...??? > > > > thanks... > > > > Ivan > > > > Hi Ivan, > > pseudo-code (for a script or so): > > - fetch all vector lengths with v.report > - calculate length - desired shortening (nice SQL excercise) > - use v.segment with > L <segment id> <line cat> <start offset> <end offset> > to create the segments at then end to be removed > - use v.overlay with NOT > > cheers > Markus -- Ti prego di cercare di non inviarmi files .doc, .xls, .ppt, .dwg. Preferisco formati liberi. Please try to avoid to send me .doc, .xls, .ppt, .dwg files. I prefer free formats. http://it.wikipedia.org/wiki/Formato_aperto http://en.wikipedia.org/wiki/Open_format Ivan Marchesini Department of Civil and Environmental Engineering University of Perugia Via G. Duranti 93/a 06125 Perugia (Italy) e-mail: [EMAIL PROTECTED] [EMAIL PROTECTED] tel: +39(0)755853760 fax (university): +39(0)755853756 fax (home): +39(0)5782830887 jabber: [EMAIL PROTECTED] _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
