[GRASS-dev] [GRASS GIS] #2936: v.net.distance: wrong directions in one-way streets

[GRASS GIS]

#2936: v.net.distance: wrong directions in one-way streets
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  Reporter:  mlennert    |      Owner:  grass-dev@…
      Type:  defect      |     Status:  new
  Priority:  normal      |  Milestone:  7.0.4
 Component:  Vector      |    Version:  svn-trunk
Resolution:              |   Keywords:  v.net.distance network one-way
       CPU:              |  direction
  Unspecified            |   Platform:  Unspecified
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Comment (by mlennert):

 Replying to [comment:5 mmetz]:
 > Replying to [comment:4 mlennert]:
 > > Nice. Just one remark: the line seems to only have a category value in
 layer 2, not in layer 1. Is that intended ?
 >
 > Not really intended, paths got all categories of their from feature.
 Changed in r67990 to match the default output of paths consisting of
 different lines.

 Works great now, thanks !

 As this is a bug, I believe that r67984, r67985 and r67990 are backporting
 candidates for grass70. At the same time they also introduce new
 functionality (line = path direction). What do you think ?


 > I got distracted by the directed graph library which is only slightly
 less difficult to read than the wxpython GUI code base.

 That makes me feel better about not having understood very much when I
 tried to find the solution myself. Thanks ! ;-)

 >
 > AFAICT, v.net.distance is now the only module using version 2 directed
 graphs. All other v.net.* modules use version 1 directed graphs. The
 directed graph library offers to create graphs (networks) of version 1, 2,
 and 3. Only version 1 graphs have been used and tested since 2003 within
 GRASS GIS.

 Sorry for my ignorance, but what are version 2 and 3 ?

 > It is not clear to me why v.net.distance copies 'from' features to the
 output but not 'to' features. Any opinion?

 I have to admit that I had never noticed that it did this... For this is
 not necessary. I would rather see v.net.distance offer the possibility to
 just output the fcat,tcat,distance values to stdout or to file, without
 creating the path vector map (which should be optional). That way it would
 even more be a network equivalent of v.distance.

 But that's for a different ticket.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2936#comment:6>
GRASS GIS <https://grass.osgeo.org>