v.distance from=pnt to=ln upload=cat column=linecat
2) For each point from vector map pnt find nearest area from map
ar within the given threshold and write the related area categories
to column areacat in attribute table attached to vector map
pnt. In case a point falls into a polygon area, the distance is zero:
v.distance from=pnt to=ar upload=cat column=areacat
3) Create a new vector map which contains lines connecting nearest
features of maps pnt and map ln. The resulting vector map
can be used for example to connect points to a network as needed for
network analysis:
v.distance -p from=pnt to=ln out=connections upload=dist column=dist
4) Query information from selected point(s). v.distance takes points from
vector as input instead of stdin. First new vector map with query points,
has to be created, then the map can be analysed:
Create query map (if not present):
echo "123456|654321|1" | v.in.ascii output=pnt
v.distance from=pnt to=map_to_query upload=cat col=somecol -p
5) Point-in-polygon: Find area from vector map ar for each point
from vector map pnt in which the individual point falls into and write
the related area categories to column areacat into attribute table
attached to vector map pnt:
v.distance from=pnt to=ar dmax=0 upload=cat column=areacat
6) Univariate statistics on results: Create a vector map containing connecting
lines and investigate mean distance to targets.
An alternative solution is to use the v.distance upload=dist option
to upload distances into the bugs vector directly, then run v.univar
on that. Also note you can upload two columns at a time.
e.g. v.distance upload=cat,dist column=nearest_id,dist_to_nr
# create working copy g.copy vect=bugsites,bugs # add new attribute column to hold nearest archsite category number v.db.addcol map=bugs column="nrst_arch INTEGER" v.distance from=bugs to=archsites to_type=point upload=to_attr \ to_column=cat column=nrst_arch out=vdistance_vectors_raw # we need to give the lines category numbers, create a table, and create # a column in that table to hold the distance data. v.category vdistance_vectors_raw out=vdistance_vectors type=line op=add g.remove v=vdistance_vectors_raw v.db.addtable map=vdistance_vectors column="length DOUBLE" v.to.db map=vdistance_vectors option=length column=length # calculcate statistics. Use v.univar.sh for extended statistics. v.univar vdistance_vectors column=length
The upload column(s) must already exist. Create one with v.db.addcol.
5.0 cmd line coordinates support: Markus Neteler, ITC-irst, Trento, Italy
5.1 update Radim Blazek, ITC-irst, Trento, Italy
Last changed: $Date$