[GRASSLIST:4010] Re: GRASS5.7

[Radim Blazek]

On Friday 23 July 2004 16:27, Du Chavoux Luyt wrote:
> Dear GRASS list
>
> I installed GRASS 5.7 and I'm really impressed! It looks like it can really
> do a lot more (at least on the vector and db side) than my old stable GRASS
> 5.03.
>
> I'm working through the tutorial now and want some clarity on the whole
> importing of shape files; more specifiacally on the effect of subsequent
> v.extract command. 
> 1. As I understand it, importing a shp file also copies
> the dbf table (to the local dbf directory) without changing it at all: is
> this correct? 

Unique column 'cat' is added.

> 2. When I do a v.extract using "where", I get a vector file
> with the subsection of the original as required. Do I also get a subsection
> of the "connected" dbf file somewhere? Is it possible to get such a
> subsection? (One alternative could be to write a generic SQL editor and
> repeat a corresponding SQL query on the dbf by itself). 

It should create new table with corresponding subset of records.

> 4. v.overlay would combine 2 vector files (union /
> intersection etc.) into a new vector file. Will it also create a connected
> dbf file for the new combined vector?

New table is created, but it contains only categories from input maps, 
not all attributes from input tables.

Radim