Find multiple points in same position

Find multiple points in same position

... applies to GPS observations, Lidar etc.

Procedure

As example, we generate 3 points in the same place.

# Generate 3 points in the same place (Spearfish60):
echo "599505|4921010|1
599505|4921010|2
599505|4921010|3" | v.in.ascii out=triple

# remove duplicates from map:
v.clean triple out=triple_simple tool=rmdupl
# ... remaining: one2many link between geometry and attributes

# verify categories:
v.category triple_simple op=report
LAYER/TABLE 1/triple_simple:
type       count        min        max
point          3          1          3
line           0          0          0
boundary       0          0          0
centroid       0          0          0
area           0          0          0
all            3          1          3

# add new layer with 1 cat/point:
v.category triple_simple out=triple_simple_multi layer=2

# create and link new table to layer 2:
v.db.addtable triple_simple_multi layer=2 columns="cat integer, count integer"
v.info -c triple_simple_multi layer=2
v.db.select triple_simple_multi
cat|int_1|int_2|int_3
1|599505|4921010|1
2|599505|4921010|2
3|599505|4921010|3
v.db.select triple_simple_multi layer=2
cat|count
1|

# upload number of identical vector points to attribute table:
# (no DBF driver)
v.to.db triple_simple_multi option=query layer=2 qlayer=1 column=count qcolumn="count(*)"
v.db.select triple_simple_multi layer=2
cat|count
1|3

# print number of points in map:
d.vect triple_simple_multi layer=2 disp=attr attrcol=count