[GRASS-user] Deleting vertices based on a list of points

Dwight Needels needels at translucida.com
Wed Jun 3 13:17:10 EDT 2009

On Jun 3, 2009, at 4:50 AM, Moritz Lennert wrote:

> On 02/06/09 20:50, Dwight Needels wrote:
>> Hi all,
>> I have two vectors: Vector A has lines and Vector B has points that  
>> share the same coordinates as a subset of the vertices in the  
>> lines. I would like to delete all of the vertices/nodes in Vector A  
>> that lie directly underneath the points in Vector B (or perhaps lie  
>> within a threshold).
>> I suspect that v.edit tool=vertexdel can do this, but I cannot  
>> figure out how to pass the coordinates of a set of points from  
>> Vector B to v.edit to be used to select vertices in Vector A for  
>> deletion. Could somebody give me a hand with this (or tell me it is  
>> not possible)?
> Feed the output of v.to.db -p option=coor on Vector B into the  
> coords= parameter of v.edit on Vector A, i.e. something like this:
> v.edit A tool=vertexdel coords=`v.to.db -p B option=coor --quiet |  
> awk -F";" '{printf"%f,%f,",$2,$3} END{printf"\n"}'`
> Moritz
Thanks! This worked great with two small changes... using "|" instead  
of ";" for the field terminator and specifying layer=2 because the  
points were generated by v.to.points, which puts the point data on  
layer 2.


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