counting the number of patches in a certain class

GRASS GRASS user
1

Hello,

I have a map of 4 classes and I would like to know the fastest way
to find the number of patches (raster polygons) within each
class. Thanks for any suggestions.

-Eric

=========================================================================
Eric Lambert
ENE Division OR GIS Labratory/Geography
P.O. Box 9005 318 Davenport Hall
Champaign, IL 61826-9005 Urbana, IL 61801

E-mail:lambert@gis.uiuc.edu Lab#: (217) 333-5919
WWW: http://ice.gis.uiuc.edu/LAESA/lambert/lambert.html

The only way I know of within standard GRASS programs is to reclass your data
into 4 binary maps, and then run r.clump on each class map. The r.le programs
by William Baker may offer alternative techniques; I'm not sure how the speed
would compare.

Good luck,
--
Malcolm D. Williamson - GIS Specialist E-mail: malcolm@cast.uark.edu
Center for Advanced Spatial Technologies Telephone: (501) 575-6159
Ozark Rm. 12 Fax: (501) 575-5218
University of Arkansas
Fayetteville, AR 72701