On 22/06/17 11:43, Markus Metz wrote:
On Thu, Jun 22, 2017 at 10:56 AM, Moritz Lennert
<mlenn...@club.worldonline.be <mailto:mlenn...@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.gisw...@gmail.com
<mailto:markus.metz.gisw...@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 <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.
v.distance -a also provides this.
While v.distance makes sense to me,
v.univar's distances to all other features do not make sense to me.
Although, I don't have a specific use case at this stage, I do think
that these can be a potentially interesting variables to geometrically
characterize a layer, for example a point layer for which this would be
a measure of general dispersal, especially when looking not only at the
average.
Moritz
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