[GRASS-user] v.digit 'next not used' cat error

Shane Litherland litherland-farm at bigpond.com
Fri Jan 7 02:15:32 EST 2011

Hi again fellow GRASSers,

Just noticed this little issue (GRASS 6.4 on ubuntu 10.04)

I am digitising boundaries, using 'no category' option, then I digitise
centroids with 'next not used' and 'add to table', where I enter
relevant info for my postgres db table. That's all fine.

I then had a couple of existing centroids where I used the 'display
categories' icon to view, and then add, an additional category to that
centroid, choosing 'add to table' option. I could then 'view attributes'
for the new second cat number, and add/edit data fields. Thereby, ending
up with two bits of data from my table, for one centroid. Again, that is
all fine.

When I returned to making new centroids, I noticed the 'next not used'
number that GRASS 'remembered' was the last cat number used when
digitising a new centroid, it did NOT recognise that I had added cat(s)
by another means to the table, and therefore should have increased the
'next not used' to suit. Instead, if I continued to just digitise the
centroid, it gave a message 'that category already exists in table' etc
and shows data for that existing cat.
I easily deleted that existing cat connection and added a new one in the
same way I added a second cat as outlined above, so it didn't affect my
db/table data at all, just a longer way of getting to the end result.

Even then though, the 'next not used' cat number had only incremented
itself by one, so if i blindly continued to digitise centroids, I would
continue to get simliar 'record exists' issue and have to manually
change/enter correct new cat and data.
To get 'next not used' to catch up, I had to use 'manual entry' for at
least one new centroid cat, then the counter for 'next not used' was
happy again.

It seems that the counter for this aspect must look up the cat numbers
in the table when starting v.digit, then increment when the 'next not
used' option is chosen whilst digitising, but it does not check
repeatedly with the db for the REAL 'next not used' cat in the db that
(as I found) can be increased by adding cats by other means.

May this have been addressed since the version of GRASS i'm using?? Or
is it something still of relevance for addressing?


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