Hi everyone,

I have a series of shapefiles that describe species distributions. Now I
would like to know the area of distribution range for each species.

First I read the shapefiles using:
spdis=readShapePoly("spdis_a")

Then I convert the SpatialPolygonDataFrame object to PolySet object, and
calculate the area of polygons using:
spdisps=SpatialPolygons2PolySet(spdis)
spdis_area=calcArea(spdisps,rollup=1)

But when polygons have holes, the results will be sum of areas of all
polygons, whether they are holes or not, which is not what I really want.

I think that there should be some solutions, but since I am new to R, I need
your help. Thanks in advance.

Sincerely,

Xin

-- 
Lin Xin
Department of Ecology,
College of Urban and Environmental Sciences
Peking University
Beijing 100871, China
Tel: +8610 62765578
Mobile: +86 15801416516
Email: linxin.pku@gmail.com

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