[R-sig-Geo] v.split.length (GRASS) in R

[Manuel Spínola]

Thank you very much Roger.



2016-11-24 8:09 GMT-06:00 Roger Bivand <Roger.Bivand at nhh.no>:

> On Thu, 24 Nov 2016, Manuel Spínola wrote:
>
> Thank you very much Roger.
>>
>> Sorry about that, I took the name from the Processing toolbox in QGIS and
>> I
>> assumed (wrongly)  that was the name in GRASS.
>>
>> I want to split a vector line (route) in equal contiguous segments of 500
>> m.
>>
>
> So for a Line object of 5km, you'd want 10 separate contiguous Line
> objects each of 500m in a Lines object? This would be the inverse operation
> to rgeos::gLineMerge(). sp::spsample can give n regular points on lines,
> but they are not a given distance apart (fixed distance, but n is given, n
> total points on the object. The code in spsample methods could give
> guidance. There are many edge cases, unfortunately, especially for typical
> input objects, which may not be clean. GRASS may be the best way of doing
> this, because it has a topological vector model, and will clean the lines
> on input.
>
> Roger
>
>
>
>> Manuel
>>
>> 2016-11-24 2:09 GMT-06:00 Roger Bivand <Roger.Bivand at nhh.no>:
>>
>> Before giving advice, please do ask for clarification. There is no
>>> v.split.length in GRASS at all, there is only v.split. Without a fully
>>> specified GRASS command, such as:
>>>
>>> v.split -n input=??, output=??, length=10.0, units="meters"
>>>
>>> which means add vertices each 10m, but do not split the vector line, we
>>> could think that the OP wants to divide a line into contiguous shorter
>>> segments. What does the OP actually want to do? Once we know that (which
>>> we
>>> do not), we can offer advice, including running the command in GRASS -
>>> which should be done anyway to ensure that the output of R-only
>>> approaches
>>> matches the desired output object.
>>>
>>> Roger
>>>
>>>
>>> On Wed, 23 Nov 2016, Manuel Spínola wrote:
>>>
>>> Dear list members,
>>>
>>>>
>>>> Is it possible to run v.split.length from GRASS in R? Or is there anyway
>>>> to
>>>> split a SpatialLinesDataFrame to shorter segments by length in R?
>>>>
>>>> Best,
>>>>
>>>> Manuel
>>>>
>>>> --
>>>> *Manuel Spínola, Ph.D.*
>>>> Instituto Internacional en Conservación y Manejo de Vida Silvestre
>>>> Universidad Nacional
>>>> Apartado 1350-3000
>>>> Heredia
>>>> COSTA RICA
>>>> mspinola at una.cr <mspinola at una.ac.cr>
>>>> mspinola10 at gmail.com
>>>> Teléfono: (506) 8706 - 4662
>>>> Personal website: Lobito de río <https://sites.google.com/site
>>>> /lobitoderio/>
>>>> Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>
>>>>
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>>>>
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>>>>
>>> --
>>> Roger Bivand
>>> Department of Economics, Norwegian School of Economics,
>>> Helleveien 30, N-5045 Bergen, Norway.
>>> voice: +47 55 95 93 55; fax +47 55 95 91 00
>>> e-mail: Roger.Bivand at nhh.no
>>> http://orcid.org/0000-0003-2392-6140
>>> https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
>>> http://depsy.org/person/434412
>>>
>>
>>
>>
>>
>>
>>
> --
> Roger Bivand
> Department of Economics, Norwegian School of Economics,
> Helleveien 30, N-5045 Bergen, Norway.
> voice: +47 55 95 93 55; fax +47 55 95 91 00
> e-mail: Roger.Bivand at nhh.no
> http://orcid.org/0000-0003-2392-6140
> https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
> http://depsy.org/person/434412
>



-- 
*Manuel Spínola, Ph.D.*
Instituto Internacional en Conservación y Manejo de Vida Silvestre
Universidad Nacional
Apartado 1350-3000
Heredia
COSTA RICA
mspinola at una.cr <mspinola at una.ac.cr>
mspinola10 at gmail.com
Teléfono: (506) 8706 - 4662
Personal website: Lobito de río <https://sites.google.com/site/lobitoderio/>
Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>

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