Michael, could you please create a PR for the documentation? On Wed, Nov 29, 2023 at 3:56 PM Michael Barton via grass-user < grass-u...@lists.osgeo.org> wrote:
> Thanks Anna and Doug, > > I did not expect it to work (thought it would be useful if it did). Rather > I was surprised by the fact that r.walk DID run and that it gave very odd > results. > > Adding to the docs is a good idea. Even better would also to have a > friction map with a negative value (min<0) raise an error in r.walk, saying > that all values in a friction map must be ≥ 0 > > Michael > _____________________________ > > C. Michael Barton > Associate Director, School of Complex Adaptive Systems ( > https://scas.asu.edu) > Professor, School of Human Evolution & Social Change ( > https://shesc.asu.edu) > Director, Center for Social Dynamics & Complexity ( > https://complexity.asu.edu) > Arizona State University > Tempe, AZ 85287-2701 > USA > > Executive Director, Open Modeling Foundation ( > https://openmodelingfoundation.github.io) > Director, Network for Computational Modeling in Social & Ecological > Sciences (https://comses.net) > > personal website: http://www.public.asu.edu/~cmbarton > > > On Nov 29, 2023, at 1:00 PM, grass-user-requ...@lists.osgeo.org wrote: > > Date: Wed, 29 Nov 2023 10:17:19 -0500 > From: Anna Petr??ov? <kratocha...@gmail.com> > To: Michael Barton <michael.bar...@asu.edu> > Cc: GRASS developers <grass-dev@lists.osgeo.org>, GRASS user list > <grass-u...@lists.osgeo.org> > Subject: Re: [GRASS-user] cost surface with negative friction odd > behavior > Message-ID: > <cae0edeofhx75u2r6qc8ek5p8czg2cd1iwr8j3vx8qiwwe8z...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > I think r.walk was not written for negative friction and while I imagine > some small (in absolute sense) negative values may work, your negative > values are pretty extreme, meaning the resulting travel time through a cell > would be negative. That can cause all kinds of issues in the algorithm. So > I would say friction should not be negative. I am not sure I would check > that in the code, because you would need to check that for each cell and I > think it's unnecessary overhead. Maybe just adding a note to documentation > may be enough. I haven't looked into the code itself, so this is just my > guess. > > Anna > > On Tue, Nov 28, 2023 at 5:48?PM Michael Barton via grass-user < > grass-u...@lists.osgeo.org> wrote: > > > _______________________________________________ > grass-user mailing list > grass-u...@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/grass-user >
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