[GRASS-dev] v.univar vs v.db.univar

[Markus Metz]

On Thu, Jun 22, 2017 at 10:56 AM, Moritz Lennert <
mlennert at club.worldonline.be> wrote:
>
> On 21/06/17 23:12, Markus Neteler wrote:
>>
>> On Wed, Jun 21, 2017 at 10:19 PM, Markus Metz
>> <markus.metz.giswork at gmail.com> wrote:
>> ...
>>>
>>> v.univar can also compute statistics on the distances between vector
>>> geometries. There is no explanation in the manual what this should be
good
>>> for. Markus N, you wanted this feature many years ago, do you remember
why?
>>
>>
>> I found this related ticket:
>> https://trac.osgeo.org/grass/ticket/942
>>
>> Checking further, I found a personal wish email to MartinL from 2009.
>> AFAIR I was dealing with LiDAR point clouds of the Trentino back
>> then... and needed to know the average distance between points

Did you really want to average distance to all other points or rather the
average distance to the nearest other point?

>> in
>> order to optimize raster binning (meanwhile I would probably use
>> r.in.xyz and count the points falling into each raster cell, then
>> r.univar on the resulting map).
>>
>> However, to have the possibility to compute statistics on the
>> distances between vector (point) geometries makes sense to me in a
>> GIS.
>
>
> Would this possibly be better done within v.distance ? Something like a
-s flag meaning "Output summary statistics of desired information" which
would take the info chosen in upload=, and possibly the -a flag and
calculated summary statistics ?

v.distance uses the distance to the nearest feature while v.univar uses all
distances to all other features. While v.distance makes sense to me,
v.univar's distances to all other features do not make sense to me.

Markus M
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