On 17/11/16 14:11, Luca Delucchi wrote:
Hi devs,
this morning I got a problem with v.select, I don't understand if is a
bug or what... I repeated the procedure with north carolina dataset
g.region vect=zipcodes -ap
v.mkgrid map=zipcodes_grid box=10000,10000
v.category zipcodes_grid opt=report
Layer/table: 1/zipcodes_grid
type count min max
point 0 0 0
line 0 0 0
boundary 0 0 0
centroid 42 1 42
area 0 0 0
face 0 0 0
kernel 0 0 0
all 42 1 42
v.select ain=zipcodes_grid bin=zipcodes operator=touches
out=zipcodes_grid_final --o
WARNING: Vector map <zipcodes_grid_final> already exists and will be
overwritten
Processing features...
100%
Processing areas...
100%
Writing selected features...
100%
Writing attributes...
WARNING: Array of values to select from column <cat> is empty
i.e. no features found which is logical, as there are no zipcode areas
that touch a grid area. 'touches' is normally defined as [1]
"a touches b: they have at least one boundary point in common, but no
interior points."
Try with intersects, overlaps, etc.
I agree though that the error message is very unclear. After the "Array
of values ... is empty" it should just stop. After a very rapid look at
main.c of v.select it seems to me that it doesn't check the result of
the selection and just goes on trying to write a new file...
Moritz
[1] https://en.wikipedia.org/wiki/DE-9IM
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