[GRASS-dev] [GRASS GIS] #3638: v.distance linear matrix remove duplicate cat column & table associated without having map of distance lines

[GRASS GIS]

#3638: v.distance linear matrix remove duplicate cat column & table associated
without having map of distance lines
-------------------------+-------------------------
 Reporter:  Maellevd     |      Owner:  grass-dev@…
     Type:  enhancement  |     Status:  new
 Priority:  normal       |  Milestone:
Component:  Vector       |    Version:  7.4.0
 Keywords:  v.distance   |        CPU:  Unspecified
 Platform:  Linux        |
-------------------------+-------------------------
 Hello,
 I would like to receive some details related to the v.distance module with
 the graphical interface in GRASS 7.4.1.

 1) When I try to generate a linear matrix of distances using v.distance, I
 observe that the output contains a duplicate column (denoted “to_cat” and
 "cat" in the example below).
 Is there a reason for that ?
 Is there a way to generate a linear matrix of distances without that
 duplicated column ?

 ==
 Here's an example command I ran:
 {{{
 v.distance -p -a from=hospitals at x to= hospitals at x upload=cat,dist
 }}}
 with the following output:
 from_cat | to_cat | cat | dist
 1 | 1 | 1 | 0
 1 | 2 | 2 | 7489.1043632983983
 1 | 3 | 3 | 339112.17046729225
 ...
 ==


 2) When creating a table associated with the distance matrix:

 a) why do my vector layers need to belong to the current mapsets while the
 goal is not to update the vector layers ?

 Example:
 ==
 Command:
 {{{
 v.distance -a from=hospitals at PERMANENT to= hospitals at PERMANENT
 output=map_connect_hospital_PERM upload=cat,dist column=to_cat,dist_min
 table=tabl_dist_PERM
 }}}

 Output: ERROR: Bug: tentative de mise à jour d'une couche qui n'est pas
 dans le jeu de cartes courant
 ==

 b) why do you have to create a map of distance lines?
 Indeed, it seems to me that it would be interesting to generate the table
 without having this map.

 Example:
 ==
 Command:
 {{{
 v.distance -a from=hospitals at x to=hospitals at x output=map_connect_hospital
 upload=cat,dist column=to_cat,dist_min table=tabl_dist
 }}}

 ==

 How to get rid of this "output = map_connect_hospital" option and just get
 the table?


 Thank you in advance for your feedback on these two concerns

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/3638>
GRASS GIS <https://grass.osgeo.org>