[GRASS-user] to shorten lines

[Markus Neteler]

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
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