[GRASS-user] SOLVED Determining number of overlapping features per location after import of shape file

[Rainer M Krug]

Hi

I managed to solve it:

    v.in.ogr dsn=./shp/ layer=fireHistory output=fireHistory
    v.category input=fireHistory output=tmpFire
    v.db.addtable map=tmpFire table=tmpFire_2 layer=2 columns='num,int'
    v.to.db map=tmpFire layer=2 qlayer=1 option=query col=num
qcol='count(*)' type=centroid

finally I can export it to a raster layer:
     v.to.rast input=tmpFire layer=2 output=mf use=attr column=num --overwrite

Could the code on the website
http://grass.osgeo.org/screenshots/vector.php please be updated, as it
is not working under grass 6.3 and less commands are necessary?

Is there a WIKI to which I could upload the code?

Thanks for your help,

Rainer

On Tue, Jun 24, 2008 at 10:32 AM, Rainer M Krug <r.m.krug at gmail.com> wrote:
> On Tue, Jun 24, 2008 at 9:57 AM, Hamish <hamish_b at yahoo.com> wrote:
>>> Is there another way of getting the number of overlapping features
>>> per cell?
>>
>> Hi,
>>
>> maybe this helps- you can try Radim's example from the vector screenshots page. (see GRASS 6.0 "Overlapping polygons" section)
>>
>> http://grass.osgeo.org/screenshots/vector.php
>>
>> Yes, funny place for tutorial material, but it demos some functionality.
>
> Thanks Hamish - I found that one alredy, but it does not work:
>
>
> OK - her is what I did:
>
>> v.category  input=fire_p output=fire_c type=centroid  option=add --o  <<-- option field=2 does not exist any more?
> WARNING: Vector map <fire_c> already exists and will be overwritten
> Building topology ...
> 3901 primitives registered
> Building areas:  100%
> 1220 areas built
> 54 isles built
> Attaching islands:  100%
> Attaching centroids:  100%
> Topology was built.
> Number of nodes     :   2735
> Number of primitives:   3901
> Number of points    :   0
> Number of lines     :   0
> Number of boundaries:   2746
> Number of centroids :   1155
> Number of areas     :   1220
> Number of isles     :   54
> Number of areas without centroid :   65
> [Raster MASK present]
>
>> echo "create table fire_c_2 (id int, num int)" | db.execute
>
>> v.db.connect map=fire_c driver=dbf layer=2 table=fire_c_2 key=id -o
> The table <fire_c_2> is now part of vector map <fire_c> and may be deleted
> or overwritten by GRASS modules
> [Raster MASK present]
>
>  > v.to.db map=fire_c layer=2 option=cat col=id  <<-- option col1=
> changed to col=
> Updating database...
>  100%
> 7 categories read from map
> 0 records selected from table
> 0 categories read from map exist in selection from table
> 6 categories read from map don't exist in selection from table
> 6 records updated/inserted
> 0 update/insert errors
> [Raster MASK present]
>
>  > v.to.db map=fire_c layer=2 qlayer=1 option=query column=num
> qcolumn="count(*)" type=centroid <<-- option col1= changed to column=
>  qcol= to qcolumn=
> Reading data from the map...
>  100%
> Querying database...
> DBMI-DBF driver error:
> SQL parser error:
> in statement:
> SELECT count(*) FROM ...
> Error in db_open_select_cursor()
>
> I guess this is a problem with the dbf database? Is there any way of
> solving this in dbf?
>
> Rainer
>
>>
>>
>> Hamish
>>
>>
>>
>>
>>
>>
>
>
>
> --
> Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
> Biology, UCT), Dipl. Phys. (Germany)
>
> Plant Conservation Unit
> Department of Botany
> University of Cape Town
> Rondebosch 7701
> South Africa
>



-- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)

Plant Conservation Unit
Department of Botany
University of Cape Town
Rondebosch 7701
South Africa