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

[Paulo van Breugel]

On 6/22/17 1:39 PM, Markus Neteler wrote:
>
> On Jun 22, 2017 11:43 AM, "Markus Metz"
> > > On 21/06/17 23:12, Markus Neteler wrote:
> > >>
>
> ....
> > >> 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?
>
> Indeed the latter...
>
> > >> in
> > >> order to optimize raster binning (meanwhile I would probably use
> > >> r.in.xyz <http://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.
>
Both could be useful. For example, when looking at dispersal distances 
to seed sources in a landscape you may be interested in the nearest 
neighbors, but also all available seed sources in a landscape.
>
> I agree.
>
> markusN
>
>
>
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