[GRASS-user] Attribute transfer from one table to another based on position of vector items

[Daniel Lee]

Hi Mike,

Ah, I understand. Yeah, that's a bit more complicated. I've had to do stuff
like that before and found a combination of raster and vector analysis
best. Check out this wiki entry:
http://grass.osgeo.org/wiki/Vector_aggregate_values

If you convert your vectors to rasters beforehand this should do the trick
for you. Note that you'll need to change the parameters in r.statistics to
give you averages rather than sums, but everything else should be almost
directly useable, if I've understood you correctly.

Best,
Daniel

--

B.Sc. Daniel Lee
Geschäftsführung für Forschung und Entwicklung
ISIS - International Solar Information Solutions GbR
Vertreten durch: Daniel Lee, Nepomuk Reinhard und Nils Räder

Softwarecenter 3
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2012/6/10 Michael Perdue <michael_perdue at yahoo.ca>

> Thanks Daniel,
>
> Unfortunately it doesn't work the way I need it to. It looks like
> v.what.vect uploads the first (or last) feature that it finds in "qmap" to
> "input". I need the values from every feature. Or better yet, the average
> of those values.
>
> Cheers,
>
> Mike
>
> On 2012-06-09, at 2:50 AM, Daniel Lee wrote:
>
> Hi Mike,
>
> Couldn't you use v.what.vect to upload the values from the lines to the
> points? They're collocated, right?
>
> Best,
> Daniel
>
> --
>
> B.Sc. Daniel Lee
> Geschäftsführung für Forschung und Entwicklung
> ISIS - International Solar Information Solutions GbR
> Vertreten durch: Daniel Lee, Nepomuk Reinhard und Nils Räder
>
> Softwarecenter 3
> 35037 Marburg
> Festnetz: +49 6421 379 6256
> Mobil: +49 176 6127 7269
> E-Mail: Lee at isi-solutions.org
> Web: http://www.isi-solutions.org
>
>
>
>
> 2012/6/9 Michael Perdue <michael_perdue at yahoo.ca>
>
>> I have a similar goal, but the solution in the case below will not work
>> for me.
>>
>> I have three points A,B & C that I have linked together through Delaunay
>> triangulation;
>>
>>        A
>>        /\
>>       /  \
>>      /    \
>>     /      \
>>    /        \
>>   /          \
>>  /____________\
>> B              C
>>
>> I want to create a new attribute for each point that is the average of
>> the length of all the lines attaching each point to it's neighbours.
>> So if;
>> B->A = 1.0m
>> A->C = 0.8m
>> C->B = 0.6m
>>
>> Then
>> A = (1.0m + 0.8m) = 0.9m
>> B = (1.0m + 0.6m) = 0.8m
>> C = (0.6m + 0.8m) = 0.7m
>>
>> Creating the Delaunay triangles and uploading the length of each face is
>> easy, but I'm not entirely clear on how to relate the length of those
>> vectors back to the points they were derived from. Any help would be
>> greatly appreciated.
>>
>> Cheers,
>>
>> Mike
>>
>>
>> On 2012-06-08, at 11:10 AM, Markus Metz wrote:
>>
>> On Fri, Jun 8, 2012 at 2:25 PM, Jaromír Kamler <kamler at centrum.cz> wrote:
>>
>> Hi,
>>
>>
>> I have two vectors imported from SHP. One contains lines (areas), which
>>
>> represents sites and in other are texts with cost of sites. I imported
>> them
>>
>> to GRASS. Texts with costs of ground are now points with cost in attribute
>>
>> table and I turned circuid lines to the areas with centroids.I need copy
>>
>> costs from attribute table of costs to the attribute table of sites
>> vector.
>>
>> I have no key for connection of this tables. Only one "key" is their
>>
>> position, because points with cost attribute are above corresponding
>> areas.
>>
>> One point with cost of ground is above one area. How get cost of
>>
>> corresponding point to the corresponding attribute of ground? I do not see
>>
>> any simple possibility.
>>
>>
>> If both vectors are available as shapefiles, you could put the two
>> shapefiles into one directory (with no other shapefiles in it) and
>> then try something like
>>
>> v.in.ogr dsn=/path/to/folder/with/shapefiles/ type=boundary,centroid
>>
>> With type=boundary,centroid, lines will be converted to boundaries and
>> points to centroids. Attributes attached to sites (points) will now be
>> attached to areas, nothing else to do.
>>
>> Markus M
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>>
>>
>>
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>>
>
>
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