[GRASS-user] [GRASSLIST:1148] Attribute editing

[Michael Barton]

Vector objects do NOT need to have a unique cat. Look at roads in the
Spearfish demo set. You can use layers to give each object a unique cat for
one layer and group them by cats in another layer.

Michael
__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton



> From: Joel Pitt <joel.pitt at gmail.com>
> Reply-To: <joel.pitt at gmail.com>
> Date: Thu, 13 Jul 2006 11:23:33 +1200
> To: Maciek Sieczka <werchowyna at epf.pl>
> Cc: <grassuser at grass.itc.it>
> Subject: Re: [GRASS-user] [GRASSLIST:1148] Attribute editing
> 
> On 7/7/06, Maciek Sieczka <werchowyna at epf.pl> wrote:
>> You can't edit a category number. You can only edit attributes (besides
>> the key column, usually and by default called "cat"). Category is a
>> unique vector feature ID - if you could edit it, you would loose
>> connection between the vactor feature and it's attributes in table.
>> Read: http://grass.itc.it/grass61/manuals/html61_user/vectorintro.html
> 
> You can edit categories with v.category can't you?
> 
> Although it seems that only systematic changes, such as adding a value
> to all categories, or generating a new category index.
> 
> Does anyone know if all vector objects MUST have a unique category?
> I have a shape file of US counties, and want to link it to a table of
> county information which have the FIPS code as a key. However, because
> counties are not all singular vector objects some have more than one
> category.
> 
> I could link the county information directly to the category numbers.
> But this would end having lots of duplicate entries where the FIPS
> code of entries is the same but with different category numbers.
> 
> Ideally I'd like to be able to use the FIPS code as the category
> number - but if category number must unique then I have to go with
> duplicate entries.
> 
> Thanks,
> 
> -- 
> -Joel
> 
> "Wish not to seem, but to be, the best."
>                 -- Aeschylus
> 
>