Markus, Moritz and Hamish -
Thanks all; some responses.
On 24/02/12 7:40 AM, Markus Metz wrote:
On Thu, Feb 23, 2012 at 8:14 PM, Hamish<[email protected]> wrote:
Moritz wrote:
If you create buffers around points which have category
values and you would like to assign those values to the buffers,
you can then (after v.category) do something like this:
v.db.addtable yourbuffers
v.db.addcol yourbuffers col="pointcat int"
v.distance from=yourbuffers to=yourpoints dmax=0
upload=cat column=pointcat
Moritz - the problem is that if the buffers are assigned a single cat to
all their centroids (even when non-overlapping), there is only one cat
value, and v.distance can't update.
Hence: v.db.select yourbuffers produces:
cat
1
rather than the 47 categories I need (because there are 47 distinct
areas in the buffer.
So: how do I reassign the cats so there are 47 instead of 1 in the buffer?
Cheers,
Richard
except of course if two of those buffers overlap, in which case it is
ambiguous as to which starting category the merged buffer area should
take. (which is why v.buffer just assigns everything to category 1 instead
of preserving seed categories in the first place)
Preserving seed categories is in theory easy, no need to assign new
category 1 to all new areas. In ambiguous cases, you could assign all
seed categories to the merged buffer area.
Markus M
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