[GRASSLIST:2688] Re: extracting vector attributes

[Christopher Fonnesbeck]

On Feb 19, 2004, at 4:14 AM, Radim Blazek wrote:

>> I am trying to determine the area of each polygon in a layer, and 
>> store
>> this statistic as a column in the attribute table (my vector 
>> attributes
>> are stored in MySQL). There appears to be no vector function in the
>> reference manual that provide this function, but I'm sure there must 
>> be
>> something that does this. Please point me in the right direction.
>
> v.to.db option=area
>
> More precisely/generally, it does not update each row in the table by 
> area size
> of each polygon, but by the sum of area sizes of all polygons with the 
> same category.

OK, it sounds like I will have to program something. I need the area of 
each polygon as an attribute field, since I am trying to classify 
stream segments by the size of the sub-basin that drains into it. The 
easiest thing, I suppose would be to take both coverages over to 
ArcView, since this is a trivial operation there (but that would be 
cheating, I guess ;-] )

C.
--
Christopher J. Fonnesbeck ( c h r i s @ f o n n e s b e c k . o r g )
Georgia Cooperative Fish & Wildlife Research Unit, University of Georgia