[GRASS-user] How to find all vectors that overlay a given region

[Michael Barton]

Sounds simple, but I think it may be tricky.

Running v.info will give you the extents of a vector file. You can parse
this and compare the extents to the region extents to see if they overlap.

You could also use the approach I gave for finding the intersection of 2
raster maps.

parse g.region -ugp vect=vector1
parse g.region -ugp vect=vector2

compare the extents of the regions defined by the vectors with extents of
the current region 

parse g.region -ugp


Michael


On 9/18/07 3:57 AM, "Patton, Eric" <epatton at nrcan.gc.ca> wrote:

> Sorry; I'll clarify. I meant how to find the number of vector maps, regardless
> of vector type, that overlay a given region. I'm really only interested in the
> map names.
> 
> ~ Eric.
> 
> 
> -----Original Message-----
> From: Michael Barton [mailto:michael.barton at asu.edu]
> Sent: Mon 9/17/2007 4:25 PM
> To: Patton, Eric; grassuser at grass.itc.it
> Subject: Re: [GRASS-user] How to find all vectors that overlay a given region
>  
> It also depends on what you mean by 'how many vectors'. Number of points,
> lines, segments, areas, centroids, etc. v.info gives some of this
> information.
> 
> Michael
> 
> 
> On 9/17/07 11:29 AM, "Patton, Eric" <epatton at nrcan.gc.ca> wrote:
> 
>> Hi,
>> 
>> I'm trying to find out how to determine how many vectors in an entire mapset
>> overlay a given region. What is the best approach to do this - import the
>> current region as a vector using v.in.region (type parameter as area), then
>> run v.select on every vector in the mapset in a loop, or is there a better
>> way? I see that v.overlay/v.select takes one map as input for both the ainput
>> and binput parameters.
>> 
>> How hard would it be to change the structures in v.select to accept multiple
>> inputs, or is this even feasible?
>> 
>> Thanks,
>> 
>> ~ Eric.
>> 
>> 
> 
> __________________________________________
> Michael Barton, Professor of Anthropology
> Director of Graduate Studies
> School of Human Evolution & Social Change
> Center for Social Dynamics and Complexity
> Arizona State University
> 
> phone: 480-965-6213
> fax: 480-965-7671
> www: http://www.public.asu.edu/~cmbarton
> 
> 

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
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