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I'm trying to build a network in GRASS in order to find the shortest path from any settlement out of 1120 (points), to one waste treatment facility out of 27 (points). I plan to use v.net.distance which is designated to this purpose, and to define source and destination points using a column called "type". In that column I have assigned the settlements layer with the number 5 and the treatment facilities with 1.

My problem occurs when I try to create the network using v.net; If I define nodes layer (nlayer=2) to be 2, I lose all the points and can't find it, even by using v.extract. Otherwise (when nlayer=1) the attributes describing type are being auromatically changed to 4, which is the type attribute for roads.

Since I have 1120 I find that using from_cat instead of a SQL restriction will be too hard.

Any one has an idea why I'm losing this crucial data and how can I prevent it from happening?

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Important bugfixes have been applied to the v.net* modules in GRASS. They will be part of the upcoming GRASS 6.4.3 release. Note, that GRASS 7 offers even more functionality for network analysis.

You may update to a GRASS 6.4.svn snapshot or a GRASS 7 snapshot to use the improved functionality already today: http://grass.osgeo.org/download/software/

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  • Thanks, Having some trouble to understand how Linux works and how to upgrade to 6.4.3 or install 7. But as I understood from Grass community ver. 7 should fix it
    – dof1985
    Mar 25, 2013 at 10:21
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    You can install both GRASS 6 and GRASS 7 versions in parallel, they don't interfere. The 6.4.3 version is not yet released but nightly snapshots (pre-releases) are available for Windows at grass.osgeo.org/download/software/ms-windows (-> SVN nightly winGRASS 6 builds, and SVN nightly winGRASS 7 builds).
    – markusN
    Mar 25, 2013 at 13:55

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