[GRASS-user] How to delete deadends?

[Achim Kisseler]

Hi,

I did something similar with a river network.

1. Make a network out of it.
2. Count lines connected to each node. (v.net option=nreport)
3. Check the lines: if a related node has only one connected line, 
delete the line.

Cheers,
Achim


Am 17.11.2010 13:49, schrieb Patrick_schirmer:
> Hi Maris,
>
> Attached you'll find an example as shp and a picture. I search for the
> lines that is highlighted in the picture, which are the only ones
> connected to more then one line.
> My approach would be to create points out of endpoints, buffer endpoints
> and count points per buffer, but I can't import v.vect.stats, as stated
> in the other post.
>
> Would be great if you or someone else in the list had an idea which
> works on GRASS 6.4.
>
> greetz,
>
> Patrick
>
>
>
> On 11/17/2010 09:57 AM, Maris Nartiss wrote:
>> Hello,
>> can You, please, send in a graphical example or put for download
>> sample data set?
>>
>> Maris.
>>
>>
>> 2010/11/15, Patrick_schirmer<patrick_GIS at gmx.ch>:
>>> Thanks Markus and Hamish,
>>>
>>> Unfortunately v.clean rmdangle will not work for me. With Threshhold<0
>>> it deletes more or less all lines, otherwise none. I guess it is because
>>> the "nests" of lines consist of 4-20 lines and are all seperated from
>>> each other.
>>> Per defintion a line "is considered to be a dangle if no other line of
>>> given /type/ is on at least one end node" (documentation v.clean
>>> rmdangle). As I am searching for lines that have exactly one line as sum
>>> of all connecting node, this tool doesn't help.
>>>
>>> I will try to solve the problem by creating points out of the line
>>> (nodes), buffering the points and delete the ones intersecting only one
>>> line. But I still hope that there is a more direct solution to delete
>>> the line as a geometry.
>>>
>>> So if there are any other suggestions I would be happy about.
>>> I'll keep you up to date in case I find a solution.
>>>
>>> Cheers, Patrick
>>>
>>>
>>>
>>> On 11/12/2010 09:51 PM, Hamish wrote:
>>>> Patrick_schirmer wrote:
>>>>
>>>>> I have a lot of lines that are linked to another
>>>>> forming various nets. Several of those lines are
>>>>> deadends. Now I search for a option to delete
>>>>> "dead-ends" within those networks. It would be
>>>>> perfect to delete the lines, or to search for the
>>>>> nodes that link to more than one line.
>>>>> I was searching in v.generalize, v.net,
>>>>> v.to.point, v.to.db but won't find the proper
>>>>> approach.
>>>>>
>>>> not a v.net specific thing, but in general for
>>>> vector maps you can use v.clean to remove (or isolate)
>>>> line "dangles" with the 'rmdangle' (or 'chdangle')
>>>> tools.
>>>>
>>>>
>>>> maybe that helps,
>>>> Hamish
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>
>
>
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