[GRASS-dev] ​Can GRASS compute the line graph representation of an input graph?

GRASS GIS GRASS GIS developer
1

Hi,

I’m interested in computing a line graph for an input graph. I couldn’t find any reference to line graphs in the GRASS docs. Is there a different term I should be using in my search or a hidden function that would create such a graph?

​I’ve posted this question on GIS.stackexchange as well, in case you prefer to answer there: http://gis.stackexchange.com/questions/146713/can-grass-compute-the-line-graph-representation-of-an-input-graph

Thanks and best wishes,
Anita

2

On 2 June 2015 at 19:46, Anita Graser <anitagraser@gmx.at> wrote:

Hi,

Hi,

I'm interested in computing a line graph for an input graph. I couldn't find
any reference to line graphs in the GRASS docs. Is there a different term I
should be using in my search or a hidden function that would create such a
graph?

I don't think so, but it seems really interesting

I've posted this question on GIS.stackexchange as well, in case you prefer
to answer there:
http://gis.stackexchange.com/questions/146713/can-grass-compute-the-line-graph-representation-of-an-input-graph

Thanks and best wishes,
Anita

--
ciao
Luca

http://gis.cri.fmach.it/delucchi/
www.lucadelu.org

3

Hi Anita,

For more sophisticated network analysis I tend to use igraph:
http://igraph.org/
It is quite easy to understand, well documented, efficient and supports also calculation of line graphs. It comes with both Python and R APIs.
Usually I feed graphs into it from GRASS (v.net) or PostGIS. I have not tried the new GDAL/OGR network driver...

Cheers
Stefan

-----Original Message-----
From: grass-dev-bounces@lists.osgeo.org [mailto:grass-dev-bounces@lists.osgeo.org] On Behalf Of Luca Delucchi
Sent: 3. juni 2015 08:41
To: Anita Graser
Cc: GRASS-dev
Subject: Re: [GRASS-dev] ​Can GRASS compute the line graph representation of an input graph?

On 2 June 2015 at 19:46, Anita Graser <anitagraser@gmx.at> wrote:

Hi,

Hi,

I'm interested in computing a line graph for an input graph. I
couldn't find any reference to line graphs in the GRASS docs. Is there
a different term I should be using in my search or a hidden function
that would create such a graph?

I don't think so, but it seems really interesting

I've posted this question on GIS.stackexchange as well, in case you
prefer to answer there:
http://gis.stackexchange.com/questions/146713/can-grass-compute-the-li
ne-graph-representation-of-an-input-graph

Thanks and best wishes,
Anita

--
ciao
Luca

http://gis.cri.fmach.it/delucchi/
www.lucadelu.org
_______________________________________________
grass-dev mailing list
grass-dev@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-dev

4

On Wed, Jun 3, 2015 at 2:41 AM, Luca Delucchi <lucadeluge@gmail.com> wrote:

On 2 June 2015 at 19:46, Anita Graser <anitagraser@gmx.at> wrote:

Hi,

Hi,

I’m interested in computing a line graph for an input graph. I couldn’t find
any reference to line graphs in the GRASS docs. Is there a different term I
should be using in my search or a hidden function that would create such a
graph?

I don’t think so, but it seems really interesting

There is a reference on wiki:

http://grasswiki.osgeo.org/wiki/Turns_in_the_vector_network_analysis

It says that line graph is created to better handle the data with turns but I’m not sure how much of this is internal and how much is exposed in some way.

Vaclav

I’ve posted this question on GIS.stackexchange as well, in case you prefer
to answer there:
http://gis.stackexchange.com/questions/146713/can-grass-compute-the-line-graph-representation-of-an-input-graph

Thanks and best wishes,
Anita

–
ciao
Luca

http://gis.cri.fmach.it/delucchi/
www.lucadelu.org

grass-dev mailing list
grass-dev@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-dev

5

On 02/06/15 19:46, Anita Graser wrote:

Hi,

I'm interested in computing a line graph for an input graph. I couldn't
find any reference to line graphs in the GRASS docs. Is there a
different term I should be using in my search or a hidden function that
would create such a graph?

The directest way I can see is to you the v.build option=dump output and then massage that data.

Moritz

6

Thanks everyone!

···

On Thu, Jun 4, 2015 at 12:54 PM, Moritz Lennert <mlennert@club.worldonline.be> wrote:

The directest way I can see is to you the v.build option=dump output and then massage that data.

​In that case, I might just start outside of GRASS, prepare the line graph, and then load the result into GRASS to finish the computations.

On Wed, Jun 3, 2015 at 10:20 PM, Vaclav Petras <wenzeslaus@gmail.com> wrote:

There is a reference on wiki:
http://grasswiki.osgeo.org/wiki/Turns_in_the_vector_network_analysis

It says that line graph is created to better handle the data with turns but I’m not sure how much of this is internal and how much is exposed in some way.

​
​That looks really promising, seems to be cutting-edge development. It seems to be more advanced than what I need but maybe it can be used nonetheless.

​Best wishes,
Anita