Hi GRASS users,
maybe someone of you can explain me following problem (of understanding) I am facing:
I want to break a single line into several. More specifically, I am using v.edit with the option break and two coordinate pairs to break a single line. I’d expect that breaking a single line at two points would result in three lines; However this results in 4 categories?!
Here a small example using the NC dataset:
#################################
Extract single line for testing
v.extract --o input=streams@PERMANENT cats=92551 output=selected_stream
Break line at two point locations and clean (recommended after v.edit break)
v.edit map=selected_stream tool=break threshold=30 coords=‘635861,224469,635793,224553’
v.clean --o input=selected_stream output=selected_stream2 tool=rmdupl
Add categories to layer 2 to check
v.category --o input=selected_stream2 layer=2 output=selected_stream3 option=add
v.db.addtable map=selected_stream3 layer=2
d.vect -c map=selected_stream3@test4 layer=2 label_layer=2 attribute_column=cat
####################################
So the display shows three colors which makes sense as these would be the three lines that I’d expect from breaking a single line at two points. But there are four categories (that are also listed in the attribute table).
Can anyone explain that to me, what I am doing wrong; or even better, what would you recommend to do if I want to break a line at two coordinates into three lines?
Thank you for your help!
Johannes
Hi all,
FYI: I just issued a new ticket in github (https://github.com/OSGeo/grass/issues/415) reporting that issue and accompanied with some more information.
/Johannes
On Fri, Mar 13, 2020 at 11:53 AM Johannes Radinger <johannesradinger@gmail.com> wrote:
Hi GRASS users,
maybe someone of you can explain me following problem (of understanding) I am facing:
I want to break a single line into several. More specifically, I am using v.edit with the option break and two coordinate pairs to break a single line. I’d expect that breaking a single line at two points would result in three lines; However this results in 4 categories?!
Here a small example using the NC dataset:
#################################
Extract single line for testing
v.extract --o input=streams@PERMANENT cats=92551 output=selected_stream
Break line at two point locations and clean (recommended after v.edit break)
v.edit map=selected_stream tool=break threshold=30 coords=‘635861,224469,635793,224553’
v.clean --o input=selected_stream output=selected_stream2 tool=rmdupl
Add categories to layer 2 to check
v.category --o input=selected_stream2 layer=2 output=selected_stream3 option=add
v.db.addtable map=selected_stream3 layer=2
d.vect -c map=selected_stream3@test4 layer=2 label_layer=2 attribute_column=cat
####################################
So the display shows three colors which makes sense as these would be the three lines that I’d expect from breaking a single line at two points. But there are four categories (that are also listed in the attribute table).
Can anyone explain that to me, what I am doing wrong; or even better, what would you recommend to do if I want to break a line at two coordinates into three lines?
Thank you for your help!
Johannes