[GRASS-user] How to extract only areas, without boundaries from a vector file ?

GRASS GRASS user
1

Hi,

Working on GRASS7 / debian, i would like to extract only areas but “v.extract --overwrite input=ZONE type=area output=ZONE_AREA” produce 1 area and 1 boundary, each of them with cat and attributes.

I would like only a vector file with cat and attributes of the areas.

If someone has a solution ?

Thanks,

yann

2

On 08/02/13 12:02, Le Jeune Yann wrote:

Hi,

Working on GRASS7 / debian, i would like to extract only areas but
"v.extract --overwrite input=ZONE type=area output=ZONE_AREA" produce 1
area and 1 boundary, each of them with cat and attributes.

I would like only a vector file with cat and attributes of the areas.

If someone has a solution ?

This means that your boundaries have cat values in ZONE already and they are just preserved. Erase those cat values before the extraction:

v.category ZONE op=del cat=-1 type=boundary out=zones_temp
v.extract input=zone_temp type=area output=ZONE_AREA

If your input does not have cat values on the boundaries, the output won't either:

GRASS 7.0.svn (nc_spm_08):~ > v.extract census_wake2000 type=area out=test_all
GRASS 7.0.svn (nc_spm_08):~ > v.category test_all op=report
Layer/table: 1/test_all
type count min max
point 0 0 0
line 0 0 0
boundary 0 0 0
centroid 105 1 105
area 105 1 105
face 0 0 0
kernel 0 0 0
all 105 1 105

Moritz

3

It works perfectly !!!

Thanks a lot !

yann

2013/2/8 Moritz Lennert <mlennert@club.worldonline.be>

On 08/02/13 12:02, Le Jeune Yann wrote:

Hi,

Working on GRASS7 / debian, i would like to extract only areas but
“v.extract --overwrite input=ZONE type=area output=ZONE_AREA” produce 1
area and 1 boundary, each of them with cat and attributes.

I would like only a vector file with cat and attributes of the areas.

If someone has a solution ?

This means that your boundaries have cat values in ZONE already and they are just preserved. Erase those cat values before the extraction:

v.category ZONE op=del cat=-1 type=boundary out=zones_temp
v.extract input=zone_temp type=area output=ZONE_AREA

If your input does not have cat values on the boundaries, the output won’t either:

GRASS 7.0.svn (nc_spm_08):~ > v.extract census_wake2000 type=area out=test_all
GRASS 7.0.svn (nc_spm_08):~ > v.category test_all op=report
Layer/table: 1/test_all
type count min max
point 0 0 0
line 0 0 0
boundary 0 0 0
centroid 105 1 105
area 105 1 105
face 0 0 0
kernel 0 0 0
all 105 1 105

Moritz

–

Yann Le Jeune
Web : http://www.paleosystem.fr/ylj_pro/