[GRASS-user] Update of vector table through selections in the map

[Andreas Philipp]

Jonathan,
I forgot some explanations and warnings, which are necessary to run this crude 
script (v.digatt):
work on a copy of your map since it is not tested and no good argument 
verification is done at the present state yet.
If you start with 
"v.digatt input=map1 output=map2 type=point col=sect ctype=INT"
all objects having no attribute in column "sect" are displayed in random 
colors and thicker, all objects already assigned to an attribute are shown 
with colors from blue to red (this is designed for numeric attributes and 
lines, but should work on points too, though has to be redesigned for points, 
areas an VARCHAR attributes). After a few checks you can zoom within your 
display to a region where you have points to work at. If you finished zooming 
(right click), you have to type in an attribute value and afterwards click on 
all objects that should get this value. I you have finished (right click) in 
this zoom region all assignments should be done by updating the table. The 
updated map will be shown and you can move your working window by zooming 
again, and so on until you say "q" for "quit" instead of typing in a 
attribute value. Hope that works, I will work more on it in order to make it 
more save an self explaining, e.g. an appropriate help function, check 
arguments and so on, but may be someone can code it in C within v.digit??? It 
is really an important function for many applications it seems. BTW (speaking 
to the list now) is it intended that r.to.vect omits to register the 
extracted vector objects and assigns no category numbers? This causes much 
trouble for subsequent processing.
Cheers,
Andreas



Am Thursday 08 June 2006 22:08 schrieb Jonathan Aguero:
> First thanks to Dylan Beaudette, Andreas Philipp, and Michael Barton for
> their answers but I guess I didn't explain myself clearly, maybe some more
> detail can help.
> I have a point map representing the intersections on centerline roads
> segments derived from the roads segment map (lines) through a several step
> process. Some of this intersections represent at-grade road intersections
> such as stop controlled intersections or signalized intersections while
> some others represent the on and off ramps in an interchange. I need to
> classify the elements in these two categories, intersections and
> interchanges. The only way to really distinguish between these two types is
> by visual inspection of the segments map and corresponding intersections
> map. So I was looking for a way of selecting several points though out the
> mouse click on the screen and then assigning a value of the attribute for
> all the selected points at the same time. This cannot be accomplished by
> database commands like v.db.update or update/where.
>
> Jonathan Aguero Valverde
>
> -----Original Message-----
> From: Michael Barton [mailto:Michael.Barton at asu.edu]
> Sent: Tuesday, June 06, 2006 12:31 AM
> To: Jonathan Aguero; grassuser at grass.itc.it
> Subject: Re: [GRASS-user] Update of vector table through selections in the
> map
>
> Use v.db.update (in the database menu)
>
> Michael
> __________________________________________
> Michael Barton, Professor of Anthropology
> School of Human Evolution & Social Change
> Center for Social Dynamics & Complexity
> Arizona State University
>
> phone: 480-965-6213
> fax: 480-965-7671
> www: http://www.public.asu.edu/~cmbarton
>
>
>
>
> From: Jonathan Aguero <jua130 at psu.edu>
> Date: Mon, 5 Jun 2006 17:11:37 -0400
> To: <grassuser at grass.itc.it>
> Subject: [GRASS-user] Update of vector table through selections in the map
>
> Dear List,
> I am trying to update the value of several records in a vector table
> simultaneously. The elements to be updated need to be selected in the map.
> I know you can update the values one by one with v.digit or using
> qgis/GRASS but I want to update several each time, something like the
> ³calculate values² in the table using ARC-GIS.
> PD: I am using pgsql for the tables.
> Any idea is welcome, thanks!
>
> Jonathan Aguero Valverde
> Research Assistant and Ph.D. Candidate
> Pennsylvania State University
> The Pennsylvania Transportation Institute
> 201 Transportation Research Building
> University Park, PA 16802
> www.personal.psu.edu/jua130
>
>
>
>
>
>
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