[GRASS-user] Multiple v.net.path parameters

[achim]

..with attachment

Hello Daniel (and others),

I ran the module successfully, but only with a network, where every line
ends with the next node.

In attached example it is possible to calc path from 1 to 4 and from 5
to 6, but not from 1 to 2,3,5,6 or from 5 to anywhere expect 6 and so on.

Do you have an idea how to handle this?

Especially: do you know if "breaking the lines" (eg. dark green one at
point 5) is possible with networking techniques?

Sorry for asking you directly, but I hopefully thought you are deep
inside the topic at the moment.

Thanks anyway for your work!
Achim



Daniel Bundala schrieb

> > Hello all,
> >
> > I have finished v.net.distance module as a part of my Google Summer of
> > Code project. The (source code of) module can be downloaded from grass
> > add-ons repository (vector/net.analyze). I recommend to download the
> > entire directory to avoid any compilation issues. Additionally, you
> > get an access to some latest network analysis modules! Anyway, simple
> > make command in the net.analyze directory should compile the modules
> > (and library). There is no documentation (yet), however, the interface
> > should be similar to the one used in v.net.path and/or v.distance.
> > Finally, here is a couple of nice pictures:
> >
> > http://people.ksp.sk/~dano/grass/nd.png
> > http://people.ksp.sk/~dano/grass/ndt.png
> > http://people.ksp.sk/~dano/grass/ndtd.png
> >
> > Blue and orange lines show the shortest length and time paths
respectively.
> >
> > Best,
> > Daniel
> >
> > On Wed, Jul 1, 2009 at 5:56 PM, Moritz
> > Lennert<mlennert at club.worldonline.be> wrote:
>> >> On 01/07/09 04:44, J. Holden wrote:
>>> >>> Hello,
>>> >>>
>>> >>> I am looking to use v.net.path to determine the distance of many
>>> >>> different points to many different other points on a network.
>>> >>>
>>> >>> Is it possible to send multiple parameters to v.net.path? For
>>> >>> instance, I have (in theory) 4 points connected to a network. I want
>>> >>> to find the distance of the line segments between points 1 and 4, 2
>>> >>> and 4, & 3 and 4.
>>> >>>
>>> >>> I want to: run v.net.path once by passing multiple parameters; get
>>> >>> vector line output of each of these three paths found by v.net.path
>>> >>> in one output file; calculate the distance of each line from the
file
>>> >>> using v.to.db.
>>> >>>
>>> >>> Since this is not a module of GRASS which I have worked with in the
>>> >>> past, I am wondering if this is possible.
>> >> Sure, as mentioned on the man page:
>> >>
>> >> "Nodes can be piped into the program from file or from stdin. The
syntax is
>> >> as follows:
>> >>
>> >> id start_point_category end_point_category
>> >>
>> >> or
>> >>
>> >> id start_point_x start_point_y end_point_x end_point_y"
>> >>
>> >>
>> >> So to take your example, and assuming that 1,2,3,4 are category
values of
>> >> existing points:
>> >>
>> >> Create a file containing:
>> >>
>> >> 1 1 4
>> >> 2 2 4
>> >> 3 3 4
>> >>
>> >> and feed it to v.net.path with the file= parameter.
>> >>
>> >> You will then get one vector map with severals lines which have
the category
>> >> values used in the first column of your file.
>> >>
>> >> Moritz
>> >> _______________________________________________
>> >> grass-user mailing list
>> >> grass-user at lists.osgeo.org
>> >> http://lists.osgeo.org/mailman/listinfo/grass-user
>> >>
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
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